Motifs | Explaining Chess

Explore chess motifs correlated with winning positions, discovered by language models using our method, BinProp.

In the paper, each model gets 100 BinProp iterations to discover a set of motifs. For the website, we take this further: we started with the Opus 5 motifs, ran 150 more iterations, and continued with other models, including 2,000+ iterations with GLM 5.3 Flash.

MotifΔ (pp)

Material or mobility advantage
+51.3
White to move
8
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1a
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White has 39 legal moves across all pieces; Black has 26. Only each side's most mobile piece or tied pieces are highlighted.
White · most mobile piece Queen on d4: 14 legal moves.
Black · most mobile piece Bishop on c8: 5 legal moves.
Python source
Material advantage for the side to move
+48.4
Black to move
1
2
3
4
5
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7
8h
g
f
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b
a
Black has 1 extra rook versus White's 1 extra bishop. At these values (bishop = 3.3 and rook = 5), Black's net edge is worth 1.7 pawns.
Black material Black's rooks on a8 and h8 and Black's bishop on c8.
White material White's bishops on f1 and d2 and White's rook on h1.
Python source
Compact pawn mass against a splintered enemy skeleton
+45.7
Black to move
1
2
3
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7
8h
g
f
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b
a
Black's pawns form 2 islands; White's split into 3. An empty file separates one island from the next.
Black island 1 1 pawn on file a.
Black island 2 4 pawns on files c–e.
White island 1 2 pawns on files b–c.
White island 2 1 pawn on file f.
White island 3 1 pawn on file h.
Python source
Bankable extra material with enemy counterplay muted
+43.1
Black to move
1
2
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5
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7
8h
g
f
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c
b
a
Black has an extra rook, while White has an extra bishop. Using standard piece values, this puts Black ahead by 2 pawns' worth of material.
Black bishop 1 bishop: g7.
White bishops 2 bishops: d2 and e2.
Black rooks 2 rooks: d8 and f8.
White rook 1 rook: a1.
Python source
Undoubled pawn-file majority on a wing
+42.6
Black to move
1
2
3
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7
8h
g
f
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b
a
Black has 4 undoubled pawn files against 2 enemy pawn files on the queenside.
Black undoubled queenside pawns 4 pawns, each on its own file.
White queenside pawns 2 pawns occupy 2 files.
Python source
Positional feature advantage
+34.8
White to move
8
7
6
5
4
3
2
1a
b
c
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f
g
h
White has 8 attacks and occupants on the four central squares, versus 4 for Black.
Central control The central squares d4, e4, d5, and e5 are occupied or attacked by White.
Controlling the centre White's rook on e1, White's bishop on d3, White's queen on f3, and White's pawn on d4 contribute to that central control.
Python source
Two-file pawn bridgehead wedge or cohesive wall vs stranded pawn
+31.7
White to move
8
7
6
5
4
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1a
b
c
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f
g
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White has no isolated pawns, while Black does. Look for the gaps beside the isolated pawns, compared with the connected files of White's pawn wall.
White cohesive pawn wall Every pawn has a friendly pawn on a neighboring file.
Black isolated pawns These pawns have no friendly pawn on either neighboring file.
Python source
More legal moves
+31.0
White to move
8
7
6
5
4
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1a
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White has 43 legal moves across all pieces; Black has 30. Only each side's most mobile piece or tied pieces are highlighted.
White · most mobile pieces Rook on a1, bishop on f2: 9 legal moves each.
Black · most mobile piece Bishop on e7: 8 legal moves.
Python source
Rook or queen on a line with no enemy pieces
+29.0
Black to move
1
2
3
4
5
6
7
8h
g
f
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b
a
Black's queen on c5 sits on the fifth rank, between the two kings. No White piece occupies that rank.
Fifth rank No White pieces occupy this rank.
Black queen No White piece attacks the queen on c5.
Kings on opposite sides The kings on h1 and g8 lie on opposite sides of the fifth rank.
Python source
More central squares occupied or attacked
+27.9
White to move
8
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1a
b
c
d
e
f
g
h
White occupies or attacks 3 of the four central squares; Black occupies or attacks 2.
White central squares Central squares occupied or attacked by this side, counted once each.
Black central squares Central squares occupied or attacked by this side, counted once each.
Python source
Own king snug in an unpressured shelter
+27.8
Black to move
1
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3
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7
8h
g
f
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b
a
Black's king on g8 has nearby pawns on f7 and h7. No enemy piece directly attacks the king or its neighbouring squares.
Sheltered king Black's king on g8.
Pawn cover Black's pawn on f7 and Black's pawn on h7.
Python source
Connected frontmost pawns
+26.4
White to move
8
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6
5
4
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1a
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White has more connected front pawns: 5 against 0.
White connected front pawns Pawns touching another front pawn, with no friendly pawn farther ahead nearby.
Python source
Queen placement and mobility
+23.5
Black to move
1
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8h
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b
a
Black's queen has 9 legal moves, meeting the minimum of five. White's queen is on its first two ranks, even with 11 legal moves.
Black queen d8: 9 legal moves.
White queen e2: 11 legal moves.
Python source
Six-sector positional scoreboard edge
+23.2
White to move
8
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1a
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h
White has fewer undefended pieces (1 versus 2) and fewer knights, bishops, rooks or queens still near home (3 versus 4).
White · undefended pieces White's bishop on f4 has no friendly defender.
Black · undefended pieces Black's bishop on g4 and Black's rook on b8 have no friendly defender.
White · pieces near home 3 knights, bishops, rooks or queens remain on the first two ranks: a1, e1, and e2.
Black · pieces near home 4 knights, bishops, rooks or queens remain on the first two ranks: b8, c8, d8, and f8.
Python source
Live pawn levers versus a frozen enemy core
+23.0
Black to move
1
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8h
g
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b
a
Black can gain space with the pawn pushes b5, f5, g5, and h5. Each is a separate option that leaves its pawn at least as well defended as attacked and does not expose the king to check.
Pawn advance b5: the pawn advances from b6 to b5, where it has at least as many defenders as attackers.
Pawn advance f5: the pawn advances from f7 to f5, where it has at least as many defenders as attackers.
Pawn advance g5: the pawn advances from g7 to g5, where it has at least as many defenders as attackers.
Pawn advance h5: the pawn advances from h7 to h5, where it has at least as many defenders as attackers.
Python source
Broad quiet dominance scoreboard
+22.3
Black to move
1
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8h
g
f
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b
a
Black's edge here comes from an open file: 1 rook occupies a pawn-free file, while White has none.
Black · open d-file The rook on d8 occupies a file with no pawns.
Python source
Long-range firepower dominance
+20.9
Black to move
1
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8h
g
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b
a
Black has 11 legal moves across rooks and bishops; White has 5. Only each side's most mobile piece or tied pieces are highlighted.
Black · most mobile piece Bishop on b2: 6 legal moves.
White · most mobile piece Rook on d1: 5 legal moves.
Python source
Quiet move threatens loose piece
+20.7
White to move
8
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1a
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White can play Bd4, attacking the undefended knight on c3.
Move The bishop moves from a7 to d4: Bd4.
New attack After the move, the bishop attacks the knight on c3.
Python source
Permanent holes in the enemy camp
+18.8
Black to move
1
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8h
g
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b
a
Black can use lasting weak squares in White's camp. Enemy pawns on adjacent files cannot advance to drive a piece away from these squares.
Weak square c4 c4 is controlled from c8 and cannot be challenged by an enemy pawn.
Weak square c3 c3 is controlled from a5 and c8 and cannot be challenged by an enemy pawn.
Weak square c2 c2 is controlled from f5 and c8 and cannot be challenged by an enemy pawn.
Weak square d3 d3 is controlled from f5 and cannot be challenged by an enemy pawn.
Python source
One-way contact dominance over an untouched army
+18.7
White to move
8
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1a
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White's knights, bishops, rooks and queens attack 3 enemy pawns or pieces. None of Black's pieces of these types attacks a White pawn or piece.
Enemy targets Units attacked by friendly knights, bishops, rooks or queens.
Attacking pieces Pieces applying the one-way contact pressure.
Python source
More rooks off their starting squares
+17.3
White to move
8
7
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1a
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h
White has 2 rooks off their starting squares; Black has 1.
White rooks off their starting squares 2 rooks stand away from the original corners.
Black rooks off their starting squares 1 rook stands away from the original corners.
Python source
Enemy pieces sharing a file
+17.3
Black to move
1
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b
a
The a-file contains 2 White non-king pieces, compared with 1 for Black. This function counts pieces as well as pawns, not just doubled pawns.
Black pieces on the a-file 1 non-king piece on this file, including pawns.
White pieces on the a-file 2 non-king pieces on this file, including pawns.
Python source
Rank-connected heavy piece coordination edge
+17.2
Black to move
1
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8h
g
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b
a
Black's rook on e8 and rook on f8 defend one another along an unobstructed line.
Coordinated heavy pieces e8 and f8 are linked by a clear rank or file.
Python source
Pawn storm race lead on the enemy king
+17.2
White to move
8
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1a
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h
White's pawn storm has reached closer to the enemy king than the opposing storm has reached White's king.
White approaching pawn The pawn on b4 is near the enemy king.
Black approaching pawn The nearest opposing pawn is on f5.
Enemy king The king on e7 faces the closer pawn.
Own king The king on e1 faces the more distant pawn.
Python source
Queenless king centralization edge
+17.1
Black to move
1
2
3
4
5
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7
8h
g
f
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c
b
a
With queens off the board, Black's king stands closer to the center than White's.
Black king The king on c6 is 1.5 squares from the board's midpoint.
White king The king on e1 is 3.5 squares from the board's midpoint.
Python source
File-by-file pawn advance lead
+17.1
White to move
8
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1a
b
c
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h
White's lead comes from files b and c; the other files are tied.
b-file White has a pawn on b3; Black has no b-pawn, so contributes zero.
c-file White's c4 pawn is 1 rank farther advanced than Black's c6 pawn.
Python source
One-way siege of unsupportable enemy pawns
+16.8
Black to move
1
2
3
4
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7
8h
g
f
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b
a
The pawn on g2 has no friendly pawn behind it on either neighboring file. Black has at least as many attackers as defenders against it, and more such targets than White.
Pawn target White's pawn on g2.
Direct attackers These pieces attack the pawn.
Python source
More undefended enemy pieces than our own
+16.3
Black to move
1
2
3
4
5
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7
8h
g
f
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d
c
b
a
White has 1 undefended piece; Black has 0.
White loose pieces White's knight on e2.
Python source
Greater piece centralization
+16.0
White to move
8
7
6
5
4
3
2
1a
b
c
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e
f
g
h
White has 3 pieces in the central area, versus 0 for Black. Pawns and kings are excluded.
White central pieces 3 knights, bishops, rooks or queens in files c–f and ranks 3–6.
Python source
Greater non-pawn reach
+15.7
White to move
8
7
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1a
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h
Across non-pawn pieces, including kings, White has 41 attacked squares in total, compared with 19 for Black, counting a square again for each piece that attacks it. Squares occupied by friendly pieces are excluded; only each side's farthest-reaching pieces are highlighted.
White · piece with greatest reach Queen on d4: 11 attacked squares without friendly occupants.
Black · piece with greatest reach Queen on c7: 10 attacked squares without friendly occupants.
Python source
Opposing minor-piece placement and reach
+15.6
Black to move
1
2
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7
8h
g
f
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c
b
a
White has 1 minor piece meeting an edge-placement or limited-reach condition; Black has none.
White knight The knight on g1 is on one of the outer two files.
Python source
More opposing minor pieces on home ranks
+15.6
Black to move
1
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8h
g
f
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b
a
White has 2 knights or bishops on its first two ranks, compared with 1 for Black.
Black home-rank minor pieces 1 knight or bishop remains on their first two ranks.
White home-rank minor pieces 2 knights or bishops remain on their first two ranks.
Python source
One-way projected heavy batteries and open-file monopoly
+15.5
Black to move
1
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3
4
5
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7
8h
g
f
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b
a
Black has 1 rook or queen on pawn-free files; White has 0. On every such file, Black has at least as many rooks or queens as White.
Black open-file pieces Heavy pieces on completely pawn-free files.
Python source
Superior pawn structure and passed pawn edge
+15.4
Black to move
1
2
3
4
5
6
7
8h
g
f
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c
b
a
Black's pawns form 2 islands, compared with 3 for White. The opponent's isolated, doubled pawns add another structural weakness.
Black island 1 Pawns on d5, a6, b6, and c7 occupy consecutive files, forming one pawn island.
Black island 2 Pawns on h5, f6, and g7 occupy consecutive files, forming one pawn island.
White island 1 Pawns on a2 and b5 occupy consecutive files, forming one pawn island.
White island 2 Pawns on d3 and d4 occupy consecutive files, forming one pawn island. Isolated and doubled on the same file.
White island 3 Pawns on f2, g2, and h4 occupy consecutive files, forming one pawn island.
Python source
Unopposed bishop reaching the enemy camp
+15.3
Black to move
1
2
3
4
5
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8h
g
f
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b
a
Black's bishop on f5 attacks the highlighted light squares. White has no bishop on that square color.
Active bishop The bishop on f5 reaches into the enemy camp.
Bishop's reach Squares reached on this bishop's diagonals.
Python source
Nearest-piece proximity to the enemy king
+15.2
White to move
8
7
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4
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1a
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h
White's nearest unit is 3 king steps from the enemy king, versus 5 in return. This distance ignores blockers and is not a move count.
White approach Nearest units: pawn on h5. The distance to the king on e8 is 3 king steps, ignoring blockers.
Black approach Nearest units: knight on b6, pawn on c6, knight on f6 and pawn on g6. The distance to the king on g1 is 5 king steps, ignoring blockers.
Python source
Worst-piece breathing-room mismatch
+15.1
White to move
8
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1a
b
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h
Among knights, bishops, rooks and queens, White's least-mobile piece reaches 2 squares without friendly occupants; Black's reaches 0.
White · least-mobile piece Bishop on g5: 2 attacked squares without friendly occupants.
Black · least-mobile piece Bishop on c8: 0 attacked squares without friendly occupants.
Python source
Banked exchange or piece bounty
+14.8
White to move
8
7
6
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2
1a
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c
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f
g
h
White has 2 extra knights, while Black has an extra bishop. Excluding pawns, this puts White ahead by 3 pawns' worth of material.
White knights 2 knights: f3 and e4.
White bishop 1 bishop: c1.
Black bishops 2 bishops: a6 and f8.
Python source
King breathing room mismatch
+13.6
Black to move
1
2
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7
8h
g
f
e
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c
b
a
Black's king has more open space nearby: 10 empty, enemy-unattacked squares within two squares, versus 3 for White.
Black king The king on e8 is the center of this area.
Black nearby open squares 10 empty, unattacked squares within two king-steps; these are not all immediate king moves.
White king The king on g1 is the center of this area.
White nearby open squares 3 empty, unattacked squares within two king-steps; these are not all immediate king moves.
Python source
Pressure on a pawn without rear pawn support
+13.4
Black to move
1
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3
4
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7
8h
g
f
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b
a
The pawn on h3 has no friendly pawn behind it on either neighboring file. Black attacks it at least as often as it is defended.
Pawn target White's pawn on h3.
Direct attackers These pieces attack the pawn.
Python source
Our pieces stand where they cannot be kicked
+13.4
White to move
8
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1a
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h
No cheaper Black piece attacks White's highlighted pieces now. The one-move test finds no cheaper-piece attack unless the attacker would itself be undefended under attack or hit by a cheaper piece.
Secure pieces White's knight on f3, White's knight on b5, and White's bishop on b6.
Python source
Enemy king stranded without shelter
+13.1
Black to move
1
2
3
4
5
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8h
g
f
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b
a
White's king has 1 highlighted shelter pawn, versus 3 for Black.
Sheltered king Black king on g8; pawn cover on f7, g7, and h7.
Exposed king White king on g2; pawn cover on g3.
Python source
Caged enemy rooks versus our deep-breaching rook
+12.2
White to move
8
7
6
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4
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1a
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f
g
h
White's rook reaches deep into the board while Black's rooks remain confined to their own side.
Active rook The rook on h5 already reaches, or has a rook line toward, the enemy's back three ranks.
Forward reach A square in the enemy's back three ranks on the rook's line.
Restricted enemy rooks These rooks and their current lines remain in their own half.
Python source
Exclusive bishop pair with no material deficit
+12.1
White to move
8
7
6
5
4
3
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1a
b
c
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f
g
h
White has 2 bishops; Black has 0.
White bishops Counted bishops: 2.
Python source
Slider fire on the breached enemy king shield
+12.0
Black to move
1
2
3
4
5
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7
8h
g
f
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b
a
Black's rook on e6 attacks e2 in front of White's king on e1, whose front row has only 1 pawn.
Attacking slider The rook on e6 attacks e2 directly.
King and front row The 3 squares directly ahead of the king contain 1 White pawn.
Attacked shield square e2 lies directly in front of the king.
Python source
Cashable pawn: on-the-spot pawn grab that survives the exchange sequence
+11.8
White to move
8
7
6
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1a
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f
g
h
White can take the pawn with Nxf5+. The rule's exchange estimate keeps White ahead after recaptures.
Move The knight moves from h4 to f5: Nxf5+.
Captured piece The pawn on f5 is captured.
Checked king The move checks the king on g7.
Python source
One-sided artillery barrage on the enemy king zone
+11.7
White to move
8
7
6
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4
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1a
b
c
d
e
f
g
h
White has 6 piece-to-square attacks into the enemy king's two-square zone; Black has 0. Pawns are included.
White attacking pieces pawn on e5: 2 zone attacks; queen on h7: 4 zone attacks.
Zone around Black's king The targets lie within two king-steps of e8. Each piece-to-square attack counts separately.
Python source
Piece concentration near the enemy king
+11.6
White to move
8
7
6
5
4
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2
1a
b
c
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f
g
h
White's king-proximity count is 27, versus 8 for Black. It weights piece types, distance to the enemy king and attacks on the king's neighbouring squares.
Pressure around Black's king Counted units on f3, c5, e5, and f6 near or attacking squares beside the king on g7.
Pressure around White's king Counted units on c4 near or attacking squares beside the king on g1.
Python source
Slider x-ray pressure through an enemy screen onto a heavier piece
+11.3
Black to move
1
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8h
g
f
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b
a
Black's queen on f6 lines up with White's rook on a1. The enemy bishop on b2 blocks the attack.
Rear piece The queen on f6 points toward the two pieces on this line.
Screen The bishop on b2 blocks the line to a1.
Target behind the screen The rook on a1 lies on the same line.
Python source
Forcing-stroke initiative surplus
+11.2
White to move
8
7
6
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4
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1a
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c
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f
g
h
White has 3 checks or exchange-winning captures; Black has 0. Nf6+ is one checking option.
Move The knight moves from e4 to f6: Nf6+.
Checked king The move checks the king on e8.
Python source
Two distant entries into a weakened enemy camp
+11.2
Black to move
1
2
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8h
g
f
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b
a
Black has two distant entry points into the enemy camp, at least three king-steps apart.
Entry point 1 d4 is an advanced pawn with no enemy pawn ahead nearby.
Entry point 2 h3 is an isolated enemy pawn that can be pressured.
Python source
Protected pawn leading the advance
+11.1
Black to move
1
2
3
4
5
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7
8h
g
f
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c
b
a
Black's defended pawn is farther advanced toward promotion than every enemy pawn.
Leading pawn The pawn on d4 is 3 rank steps from promotion.
Defenders Friendly pieces defend this leading pawn.
Enemy's leading pawns The closest enemy pawns are 4 rank steps from promotion.
Python source
Safe piece infiltration in enemy territory
+10.8
White to move
8
7
6
5
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1a
b
c
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f
g
h
White's queen on a8 is securely posted in Black's half. Enemy pawns cannot attack it now or after one push; the highlighted targets or empty attacked squares show its activity.
Secure advanced post White's queen on a8 holds a safe advanced post.
Targets Black's bishop on c8 is attacked from a8.
Python source
Pawn-space edge in opponent half
+10.8
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's pawns make 6 attacks into Black's half, versus 3 in return. Multiple pawns attacking the same square count separately.
White pawn control 6 pawn attacks into the opponent's half; repeated attacks count separately.
Black pawn control 3 pawn attacks into the opponent's half; repeated attacks count separately.
Advanced pawns d5 has crossed the middle of the board.
Python source
Safe fresh-threat move surplus over a silenced opponent
+10.8
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has 9 moves that create a better-supported attack, versus 0 for White. Qc7 attacks the bishop on c6.
Move The queen moves from d8 to c7: Qc7.
New attack After the move, the queen attacks the bishop on c6.
Python source
Enemy army bottled behind the midline under our bridgehead
+10.7
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has a piece beyond the midline, while no enemy pawn or non-king piece has reached White's first three ranks.
Bridgehead The piece on e5 has crossed into enemy territory.
Python source
Pawn-supported advanced minor piece
+10.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's advanced knight has pawn support and at least as many defenders as non-king attackers.
Advanced minor The knight on f6 is not currently attacked by an enemy pawn.
Pawn support These pawns defend the advanced minor piece.
Python source
Rooks and queens with no friendly pawn ahead
+10.4
Black to move
1
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8h
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b
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Black has more rooks or queens with no friendly pawn ahead on their files.
Black rooks and queens 2 rooks or queens have no friendly pawn ahead on their file.
White rooks and queens 1 rooks or queens have no friendly pawn ahead on their file.
Python source
Space-gaining pawn wedge in the centre
+10.3
Black to move
1
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8h
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b
a
Black's pawn on e5 supports the pawn on d4, forming an advanced central chain. The highlighted squares show their control in White's half.
Central pawn chain e5 supports d4.
Space controlled The pawns control c3, e3, and f4 in the enemy half.
Python source
Existing double attack by one piece
+10.3
White to move
8
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White's queen on g3 attacks Black's rook on d6 and pawn on g6 at once.
Attacker White's queen on g3.
Double attack It already attacks d6 and g6.
Python source
Opponent starved of forcing resources
+10.1
White to move
8
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White's bishop on c1 can move to g5, giving a safe check to Black's king on e7. White has 3 forcing moves, versus 0 for Black.
Key pieces White's bishop on c1.
Targets Black's king on e7.
Move or pressure square g5.
Python source
Queen restriction or a checking edge
+9.9
White to move
8
7
6
5
4
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1a
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White has 5 legal checking moves, compared with 0 for Black. The highlighted pieces are the ones that can give check.
White checking pieces These pieces supply 5 legal checking moves in total.
Python source
Mobile queen against limited opposing queen reach
+9.7
Black to move
1
2
3
4
5
6
7
8h
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b
a
Black's queen is free to act, while White's queen has only 2 unattacked destinations along its lines.
Black queen The queen on e5 is unattacked and has 18 legal moves.
White queen The queen on f3 has 2 destinations that are neither friendly-occupied nor attacked by Black.
Python source
Stranded enemy king or safe double strike
+9.6
White to move
8
7
6
5
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White can play Qe7: the queen attacks the rook on d8 and the rook on f8.
Move The queen moves from c5 to e7: Qe7.
Fork targets After the move, the queen attacks the rook on d8 and the rook on f8.
Python source
Passed pawn majority edge
+9.6
Black to move
1
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b
a
Black has more passed pawns: no enemy pawn remains ahead on their file or a neighboring file.
Black passed pawns 1 pawn meets this condition.
Python source
Opponent lags in mobilization and king shelter
+9.5
White to move
8
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Black's knights on c8 and g8 remain on the back rank, versus no back-rank knights or bishops for White. Black's king on f8 is also less securely placed.
Back-rank knights and bishops Black's knights on c8 and g8 remain on the back rank.
Awkward king Black's king on f8 also has the less secure placement.
Python source
Pressure on weak squares around the enemy king
+9.5
White to move
8
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5
4
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1a
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White's pieces concentrate pressure on nearby squares around Black's king. 3 of the highlighted attacked squares have no non-king defender.
Attacking team White's bishop on c4, White's pawn on f4, and White's rook on a8 attack squares around the enemy king.
King under pressure Black's king on d7; attacked nearby squares b5, d5, e5, e6, c8, d8, and e8.
Python source
Slider battery reinforced and trained on the enemy king
+9.5
Black to move
1
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8h
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b
a
Black's bishop on d4 attacks f2 beside White's king, while the queen on b6 supports it.
Front attacker The bishop on d4 attacks f2.
Supporting slider The queen on b6 defends the front piece.
King-side target f2 lies beside the king on g1.
Python source
Heavy-piece pressure on the enemy pawn rank
+9.4
Black to move
1
2
3
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5
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8h
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b
a
Black's heavy piece attacks pawns on White's second rank.
Attacking heavy piece The rook on b8 reaches the enemy pawn rank.
Pawn-rank targets Enemy pawns on their original pawn rank, attacked along the heavy piece's line.
Python source
Free bishop against pawn-strangled enemy bishop
+9.3
White to move
8
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1a
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White's bishop has open diagonals, while an enemy bishop is hemmed in by its pawn structure.
White bishop The bishop on e3 has 9 unobstructed diagonal squares.
Black bishop The bishop on f8 has 0 unobstructed diagonal squares.
Python source
Discovery-fork-initiative
+9.1
Black to move
1
2
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8h
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b
a
Black has 1 knight-fork option, versus 0 for White. The colors link each jump with its simultaneous targets.
Black fork move Nb3: the knight moves from c5 to b3.
Black fork targets The knight attacks these targets at the same time after its move.
Python source
Knight fork of a heavy piece and another target
+8.9
White to move
8
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White can play Nf4: the knight attacks the rook on h3 and the pawn on g6.
Move The knight moves from e2 to f4: Nf4.
Fork targets After the move, the knight attacks the rook on h3 and the pawn on g6.
Defenders after the move These pieces defend the destination f4 after the move.
Python source
Ripe undefended enemy target capturable right now
+8.8
White to move
8
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White can play Nxd5, taking the undefended pawn on d5.
Move The knight moves from c7 to d5: Nxd5.
Captured piece The pawn on d5 is captured.
Python source
Opposing rooks on their starting squares
+8.8
White to move
8
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h
Both Black rooks are on their starting squares.
Black rooks Both rooks occupy their original corners.
Python source
Heavy piece raiding the enemy second rank
+8.7
Black to move
1
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8h
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b
a
Black's heavy piece can reach the enemy's second rank along an open line, with a pawn target along that rank.
Entry piece The heavy piece on a8 has an unobstructed line to the entry square.
Entry square The empty square a2 is on the enemy's second rank.
Pawn along the rank From the entry square, the line toward c2 is clear.
Python source
Pressure on the opponent weak pawns
+8.6
White to move
8
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1a
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h
Black's pawn on b5 is attacked by 2 White pieces and has 0 defenders.
Weak pawn Black's pawn on b5 is the target.
Attackers White's knight on c3 and White's bishop on c4 attack b5.
Python source
Rook on a file without enemy pawns or major pieces
+8.4
White to move
8
7
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4
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1a
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White's rook on h1 occupies a file with no Black pawn, rook or queen.
Uncontested rooks h1: no enemy pawn, rook or queen occupies this file.
Python source
Central pawn wedge lead
+8.0
Black to move
1
2
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6
7
8h
g
f
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b
a
Black has more pawns in the central belt: 3 versus 0.
Black central-belt pawns 3 pawns on the c–f files and fourth or fifth ranks.
Python source
Pawn majority on one or both wings
+8.0
White to move
8
7
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1a
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White has a pawn majority: 4–2 on the queenside (a–c).
White queenside 4 pawns on files a–c.
Black queenside 2 pawns on files a–c.
Python source
Opponent saddled with a bad minor piece
+8.0
White to move
8
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1a
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g
h
Black's bishop on f8 is hemmed in by its own pawns on d6 and g7.
Restricted minor Black's bishop on f8.
Blocking pawns Black's pawns on d6 and g7 block its diagonals.
Available square Only e7 remains reachable outside enemy pawn control.
Python source
Dynamic pawn levers and safe advances
+7.9
Black to move
1
2
3
4
5
6
7
8h
g
f
e
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b
a
Black's pawn-activity count is 9, versus 4 for White. It rewards attacks on pieces and clear forward squares, without checking legal moves.
Black pawn play Pawns contributing through attacks on pieces or clear forward squares; legal moves are not checked.
White pawn play Pawns contributing through attacks on pieces or clear forward squares; legal moves are not checked.
Python source
Enemy heavy pieces harassed by our lesser units
+7.6
White to move
8
7
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1a
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White's pawn on b2 can move to b4, attacking Black's queen on a5 with a cheaper unit.
Threatening move White's pawn on b2 and Empty square b4.
Heavy-piece target Black's queen on a5.
Python source
Greater queen reach
+7.6
White to move
8
7
6
5
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1a
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c
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h
White's queen attacks or defends 14 squares, versus 10 for Black; 10 of its destinations are in the enemy half.
White queen The queen on a6 attacks or defends 14 squares.
Black queen The queen on d8 attacks or defends 10 squares.
Python source
Direct contact-count edge
+7.6
Black to move
1
2
3
4
5
6
7
8h
g
f
e
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b
a
Black makes 4 direct attacks on enemy pawns or pieces, versus 0 for White. Each attacker-target pair counts separately; kings are excluded.
Black contacts 4 direct attacks, counting each attacker–target pair.
Python source
Immediate king-pawn cover advantage
+7.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
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b
a
Black has 3 pawns directly shielding its king; White has 1.
Black immediate pawn cover 3 pawns on the rank directly ahead of the king, on its file or a neighbouring file.
White immediate pawn cover 1 pawn on the rank directly ahead of the king, on its file or a neighbouring file.
Python source
One-way deep queen berth in the enemy camp
+7.3
White to move
8
7
6
5
4
3
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1a
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c
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g
h
White's queen attacks squares around the enemy king, while Black's queen has no corresponding pressure.
Attacking queen The queen on d1 attacks the enemy king's neighborhood.
Pressure near the king Squares beside the king reached by the queen.
Enemy king The king on d7 faces this pressure.
Python source
Winning capture with no counter-strike
+7.3
Black to move
1
2
3
4
5
6
7
8h
g
f
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b
a
Black can capture the highlighted rook and win a full rook's value. White has no immediate capture of comparable value.
Capturing rook Black's rook on d8.
Rook to win White's rook on d6.
Python source
Rook aligned behind a movable pawn
+7.3
Black to move
1
2
3
4
5
6
7
8h
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f
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b
a
Black's rook and pawn line up with White's queen. The pawn still blocks the rook's attack.
Black rook The rook on f8 is behind its own pawn.
Blocking pawn The pawn on f7 blocks the rook's path to the queen.
White queen The queen on f4 lies beyond the pawn.
Python source
Safe checking tempo in hand
+7.3
White to move
8
7
6
5
4
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1a
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White can play Qxe6+, which captures the pawn on e6.
Move The queen moves from e2 to e6: Qxe6+.
Captured piece The pawn on e6 is captured.
Checked king The move checks the king on e8.
Python source
Connected rooks with enemy rooks split
+7.1
White to move
8
7
6
5
4
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1a
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c
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g
h
White's rooks on c1 and d1 share a rank with no piece between them. Black has no such rook pair.
Connected rooks c1 and d1 share a clear rank.
Black rooks The opponent has no connected rook pair.
Python source
Rook or queen pressure near the king
+7.1
White to move
8
7
6
5
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1a
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f
g
h
Qf5 keeps pressure on h7, the pawn beside Black's king on g8.
Move The queen moves from d3 to f5: Qf5.
King shelter Pawn: h7. King: g8.
Python source
Concrete exchange-winning capture on a defended enemy piece
+7.0
Black to move
1
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7
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b
a
Black attacks the defended bishop on d4. The rule's exchange estimate gives a gain of 1 material point.
Defended target The bishop on d4 is the exchange target.
Attacking pieces These pieces attack the target.
Defenders These pieces defend the target and enter the exchange calculation.
Python source
Safe queen fork on two enemy units
+7.0
White to move
8
7
6
5
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2
1a
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c
d
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f
g
h
White can play Qd3, attacking 2 targets at once.
Move White can play Qd3: d1 to d3.
Targets Attacked after the move: bishop on d6 and pawn on h7.
Python source
Loaded x-ray battery aimed deep into the enemy camp
+6.9
White to move
8
7
6
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2
1a
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c
d
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f
g
h
White's rook on f1 lines up with Black's bishop on f5. The friendly knight on f4 blocks the attack.
Rear piece The rook on f1 points toward the two pieces on this line.
Screen The knight on f4 blocks the line to f5.
Target behind the screen The bishop on f5 lies on the same line.
Python source
Cage dominance over an imprisoned enemy piece
+6.9
Black to move
1
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3
4
5
6
7
8h
g
f
e
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c
b
a
White's piece is hemmed in: its available exits are tightly controlled.
Restricted enemy piece The piece on f1 has very little safe room.
Controlled exits The piece's empty exit squares are covered or restricted.
Python source
Punishable caged enemy piece
+6.8
White to move
8
7
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1a
b
c
d
e
f
g
h
Black's piece is hemmed in: its available exits are tightly controlled.
Restricted enemy piece The piece on b8 has very little safe room.
Controlled exits The piece's empty exit squares are covered or restricted.
Python source
Safe bishop or rook plunge forming a double attack on a falling target
+6.6
Black to move
1
2
3
4
5
6
7
8h
g
f
e
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b
a
Black can play Rxb2: the rook attacks the pawn on a2 and the bishop on d2.
Move The rook moves from b8 to b2: Rxb2.
Captured piece The pawn on b2 is captured.
Fork targets After the move, the rook attacks the pawn on a2 and the bishop on d2.
Python source
Opponent pieces tied to passive defence
+6.6
Black to move
1
2
3
4
5
6
7
8h
g
f
e
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c
b
a
4 of White's pieces defend attacked pawns or block a passed pawn. The highlighted pairs show each defender or blocker with its target.
Defensive duty White's rook on f1 defends f3.
Defensive duty White's queen on c2 defends c4.
Defensive duty White's knight on a3 defends c4.
Defensive duty White's bishop on d3 defends c4; blockades d4.
Python source
Queen reach imbalance
+6.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's queen reaches 14 squares, versus 6 for Black; 6 of its destinations are in the enemy half.
White queen The queen on c4 reaches 14 squares without friendly occupants.
Black queen The queen on d8 reaches 6 squares without friendly occupants.
Python source
Pawn fork resource
+6.6
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black can play fxe4, attacking 2 targets at once.
Move Black can play fxe4: f5 to e4.
Targets Attacked after the move: pawn on d3 and pawn on f3.
Python source
Fewer separated pawn ranks
+6.5
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's pawns occupy 1 unbroken band of ranks; Black's occupy 2. An empty rank separates one band from the next.
White rank band 1 Pawns occupy adjacent ranks within this band.
Black rank band 1 Pawns occupy adjacent ranks within this band.
Black rank band 2 Pawns occupy adjacent ranks within this band.
Python source
Two-front squeeze against the enemy camp
+6.5
White to move
8
7
6
5
4
3
2
1a
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c
d
e
f
g
h
White has pressure on both wings, forcing the defender to attend to two distant fronts.
King-wing pressure Pieces or advanced pawns establishing pressure on the king's wing.
Far-wing target The attacked unit on f4 is on the other wing.
Python source
Safe checking resource
+6.4
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White can give check with Rxd5+ while keeping the checking piece defended.
Move White can play Rxd5+: d1 to d5.
Targets Attacked after the move: king on d8.
Support The moved piece is defended by e4.
Python source
Deep protected spearhead pawn
+6.4
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's defended pawn holds an advanced foothold without being attacked by an enemy pawn.
Advanced pawn The pawn on d4 is on its 5th rank.
Support These friendly pieces defend the advanced pawn.
Python source
Advanced decentralized knight outpost
+6.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's defended knight on d5 attacks 8 squares and is not attacked by a White pawn. White has no knight meeting those conditions on its fourth rank or farther forward.
Knight outpost d5 is defended.
Support Direct defenders: b6, e6 and d8.
Python source
Fewer pieces on their starting squares
+6.3
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has no knights or bishops on the original minor-piece squares. Black has 2 knights, bishops or queens on the original minor-piece or queen squares.
Black home-rank minor pieces 1 knight or bishop remains on the original minor-piece squares.
Black queen at home The queen occupies its original square.
Python source
One-sided pins and loaded discovered lines
+6.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's queen on a5 pins the knight on d2 to the king on e1. Moving it off this line would expose the king to check.
Pinned piece The piece on d2 shields its king.
Pinning piece Moving the pinned piece off this line would expose its king.
King behind it The king on e1 is behind the pinned piece.
Python source
Ready-made pin and skewer squares for our sliders
+6.2
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's rook on a1 can move to d1, lining up Black's knight on d6 in front of Black's queen on d8.
Slider move White's rook on a1 and Empty square d1.
Front target Black's knight on d6.
More valuable target Black's queen on d8.
Python source
Connected slider lines toward the enemy king zone
+6.2
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has 1 connected slider pair whose continued line reaches a major piece or the king's three-square zone; Black has 0.
White connected sliders 1 qualifying pair shares clear lines.
White line endpoints The continued lines reach an enemy major piece or a square within three king-steps of e8.
Python source
Multiple attackers on a single weakly defended enemy piece
+6.0
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
White's pawn on a5 has 2 Black attackers and 0 White defenders.
Attackers a8 and d8 apply the pressure.
Under-defended targets a5 has at least two attackers and at most one defender.
Python source
Enemy pieces nailed by pins and x-rays
+5.9
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's queen on e5 lines up with Black's king on e8. The enemy pawn on e6 blocks the attack.
Rear piece The queen on e5 points toward the two pieces on this line.
Screen The pawn on e6 blocks the line to e8.
Target behind the screen The king on e8 lies on the same line.
Python source
Connected pawn fronts with clear files
+5.9
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has adjacent pawn fronts with no enemy pawn ahead on their files; White has no such pair.
Connected pawn fronts a6 and b7 occupy neighboring files, with no enemy pawn ahead on those same files.
Python source
Skewer xray winning material
+5.9
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's queen on f6 lines up with White's queen on c3. The enemy pawn on d4 blocks the attack.
Rear piece The queen on f6 points toward the two pieces on this line.
Screen The pawn on d4 blocks the line to c3.
Target behind the screen The queen on c3 lies on the same line.
Python source
Safe rook or bishop fork on valuable enemy units
+5.9
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White can play Rxd5+, attacking 3 targets at once.
Move White can play Rxd5+: d1 to d5.
Targets The checked king and 2 other targets: bishop on c5, knight on e5 and king on d8.
Python source
King on a castling square with a full pawn shield
+5.8
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's king on g8 has all three wing pawns on their starting squares. White has 1 pawn on the corresponding squares near its king.
Black king shelter 3 wing pawns are on original pawn squares; this does not establish castling history.
White king shelter 1 wing pawn is on original pawn squares; this does not establish castling history.
Python source
Material lead with a king near the promotion route
+5.8
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black is a pawn's worth of material ahead. Its king is 3 king-steps from the opposing pawn's promotion square; the pawn needs 5 advances.
Black knight 1 knight: c6.
Black bishops 2 bishops: c8 and f8.
White bishop 1 bishop: h6.
Black rook 1 rook: a8.
White rooks 2 rooks: d1 and g3.
White passed pawn The pawn on h3 is 5 rank steps from promotion on h8.
Black king The king on e8 is 3 king steps from that promotion square, ignoring blockers and attacks.
Python source
Protected pawn chain edge
+5.8
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has more pawns supported by pawns: 2 versus 0 for Black.
White pawns supported by pawns Counted pawns supported by pawns: 2.
Python source
Multi-file piece penetration edge
+5.8
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has pawns or pieces in Black's half on 2 files; Black has them in White's half on 1 file.
White invaders These pieces occupy 2 different files in the enemy half.
Black invaders These pieces occupy 1 file in the enemy half.
Python source
Equal-bishop activity edge
+5.8
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's bishop has 9 attacks on squares without friendly pieces, versus 3 for White. These are attacks, not necessarily legal moves.
Black bishop The bishop whose reach is compared.
Black reach 9 attacks on squares without friendly pieces; repeated attacks count separately, not as legal moves.
White bishop The bishop whose reach is compared.
White reach 3 attacks on squares without friendly pieces; repeated attacks count separately, not as legal moves.
Python source
Pawn structure soreness edge
+5.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's pawns form 2 islands; White's split into 3. An empty file separates one island from the next.
Black island 1 2 pawns on files a–b.
Black island 2 4 pawns on files e–h.
White island 1 1 pawn on file a.
White island 2 2 pawns on file c.
White island 3 3 pawns on files f–h.
Python source
Same-file alignment with a movable piece
+5.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's bishop and knight share a file with Black's queen. This alignment does not give the bishop a straight-line attack.
White bishop The bishop on e3 shares this file with the other two pieces.
Intervening knight The knight on e5 is between the bishop and queen.
Black queen The queen on e8 lies on the same file.
Python source
Deep-penetration assets: seventh-rank heavyweight or near-queening passer
+5.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's queen on h7 has reached the enemy's last three ranks, attacking g6 and f7.
Invading heavy piece The queen on h7 is inside enemy territory.
Enemy targets Pieces attacked by the invader.
Python source
Same-file alignment with a movable piece
+5.5
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's bishop and bishop share a file with White's bishop. This alignment does not give the bishop a straight-line attack.
Black bishop The bishop on f6 shares this file with the other two pieces.
Intervening bishop The bishop on f5 is between the bishops.
White bishop The bishop on f4 lies on the same file.
Python source
Unassailable advanced pawn wedge
+5.5
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has more protected pawns across the midline with no clear path for an enemy pawn to attack them.
White protected wedge pawns These pawns are advanced and defended; no enemy pawn has a clear route to attack them.
Python source
Pin or skewer xray
+5.4
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's queen on a6 lines up with White's king on e2. The enemy queen on d3 blocks the attack.
Rear piece The queen on a6 points toward the two pieces on this line.
Screen The queen on d3 blocks the line to e2.
Target behind the screen The king on e2 lies on the same line.
Python source
Queen harasses more enemy units than enemy queen harasses ours
+5.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's queen attacks more enemy units: 2 versus 0.
Black queen Attacks 2 enemy units.
Black targets The enemy units this queen attacks.
White queen Attacks 0 enemy units.
Python source
One-way standing double strike or queen liberty mismatch
+5.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has more ready double attacks than White, with valuable or undefended targets among them.
Black double attackers Safe pieces attacking at least two enemy units.
Black simultaneous targets Targets attacked by these double attackers.
Python source
Free landing squares across the frontier
+5.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has more uncontested landing squares across the midline: 4 against 1.
Black entry pieces These pieces have quiet moves across the midline.
Black free landing squares Empty enemy-half squares that are not currently attacked by the enemy.
White entry pieces These pieces have quiet moves across the midline.
White free landing squares Empty enemy-half squares that are not currently attacked by the enemy.
Python source
Few unattacked destinations for the opposing queen
+5.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
White's queen has only 2 unattacked destinations along its lines.
Restricted queen The queen on f3 has 2 destinations that are neither friendly-occupied nor attacked by Black.
Unattacked destinations The remaining destinations along the queen's lines that are not attacked.
Python source
Safe knight fork on a king, queen, or rook
+5.3
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black can play Nc2, attacking 2 targets at once.
Move Black can play Nc2: b4 to c2.
Targets Attacked after the move: rook on a3 and pawn on d4.
Python source
Queenless endgame regimen edge
+5.3
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's king sits closer to the centre of its own pawn group, and its best rook reaches 8 empty squares versus Black's 2.
White · king and pawns The king is closer to the centre of its own pawn group.
Black · king and pawns The king is farther from the centre of its own pawn group.
White · rook reach The rook on d1 reaches 8 highlighted empty squares.
Black · rook reach The rook on e8 reaches 2 highlighted empty squares.
Python source
Seventh-rank heavy invasion or absolute-pin surplus
+5.2
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's queen on a1 has reached the enemy's last three ranks, attacking b1 and a3.
Invading heavy piece The queen on a1 is inside enemy territory.
Enemy targets Pieces attacked by the invader.
Python source
One-move safe entries into the enemy half
+5.2
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has 2 legal knight, bishop, rook or queen moves from its half into Black's half, versus 0. Destinations are unattacked before moving.
White advance options 2 moves into enemy territory: Bxe5, Ba5+.
Python source
Protected advanced pawn wedge
+5.2
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's defended pawn on e5 is in Black's half and not attacked by a Black pawn. Black has no pawn meeting the same conditions.
Supported advance e5 is defended.
Support Direct defenders: g3.
Python source
Pending tactic tips the material balance
+5.1
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's bishop on b7 can capture White's rook on h1. The exchange estimate is a gain of 2 material points, enough to put Black ahead.
Capturing piece Black's bishop on b7.
Tactical gain White's rook on h1.
Python source
Advanced outside pawn majority
+5.1
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has a 4–3 pawn majority on the queenside, away from the enemy king.
White queenside 4 pawns on this wing.
Black queenside 3 pawns on this wing.
Enemy king The comparison uses the opposite wing.
Python source
Playable pawn majority on the wing away from the enemy king
+5.1
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has a pawn majority: 4–2 on the queenside, away from the enemy king.
Black queenside 4 pawns on files a–d.
White queenside 2 pawns on files a–d.
Room ahead A majority pawn has an empty square directly ahead.
Python source
Unattacked king-neighbour squares
+5.1
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has 3 currently unattacked squares beside its king, versus 0 for Black.
White king The king on e1 has 3 such neighbouring squares.
White unattacked neighbours No friendly piece occupies these squares, and they are currently unattacked by the enemy.
Black king The king on e8 has 0 such neighbouring squares.
Python source
Attacking pawn majority around enemy king
+5.1
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has a 4–3 pawn majority on the kingside.
White kingside 4 pawns on this wing.
Black kingside 3 pawns on this wing.
Enemy king The comparison uses the king's wing.
Python source
Permanent piece blockade of enemy pawns
+5.1
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has 1 piece blockade of enemy pawns, versus 0 for Black. No enemy pawn on an adjacent file is behind a blockader, so a straight pawn advance cannot attack its square.
White blockaders White's queen on h5.
Stopped enemy pawns Black's pawn on h6.
Python source
Greater knight reach
+5.0
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's knights have 10 distinct attacked squares, versus 0 for Black. These are attacks, not necessarily legal moves.
White knights The knights whose reach is compared.
White reach 10 attacked squares, including friendly-occupied squares; each square counts once.
Python source
Netted enemy passed pawns
+4.9
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Each White passed pawn has a specific obstacle: a blockade, direct pressure, or control of its advance or promotion square.
Enemy passed pawns These pawns have no opposing pawn ahead on their own or neighboring files.
Occupied promotion square A friendly piece occupies the promotion square.
Python source
Deep pawn-shielded knight outposts unchallenged by enemy pawns
+4.9
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has 1 advanced knight defended by pawns; White has 0. No enemy pawn is one or two ranks ahead on either neighboring file of these knights.
Black knight posts No enemy pawn is one or two ranks ahead on either neighboring file.
Black pawn anchors These pawns defend the highlighted knight posts.
Python source
Loaded discovered attack down an open line
+4.9
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's rook on d1 lines up with Black's queen on d6. The friendly pawn on d4 blocks the attack.
Rear piece The rook on d1 points toward the two pieces on this line.
Screen The pawn on d4 blocks the line to d6.
Target behind the screen The queen on d6 lies on the same line.
Python source
Rook aligned behind a movable pawn
+4.9
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's rook and pawn line up with White's bishop. The pawn still blocks the rook's attack.
Black rook The rook on f7 is behind its own pawn.
Blocking pawn The pawn on f6 blocks the rook's path to the bishop.
White bishop The bishop on f4 lies beyond the pawn.
Python source
Opponent moves keep walking into loss of material
+4.8
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
If White's knight on f3 moves to g5, Black's pawn on f6 attacks it there.
Key pieces Black's pawn on f6.
Targets White's knight on f3.
Move or pressure square g5.
Python source
King-front pawn wedge against a sealed enemy camp
+4.7
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's defended pawn has advanced beside the enemy king, while enemy units have not reached White's first three ranks.
Advanced pawn The pawn on f6 is on its 6th rank.
Support These friendly pieces defend the advanced pawn.
Enemy king The advanced pawn is on the king's file or a neighboring file.
Python source
Quiet double threat while opponent has no free capture
+4.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black can play Nb6: the knight attacks the queen on a4 and the knight on c4.
Move The knight moves from d5 to b6: Nb6.
Fork targets After the move, the knight attacks the queen on a4 and the knight on c4.
Defenders after the move These pieces defend the destination b6 after the move.
Python source
Pawn-protected pieces versus hanging enemy pieces
+4.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has 2 pieces defended by pawns; White has 2 pieces with no defender.
Pawn-supported pieces 2 Black pieces are protected by pawns.
Undefended enemy pieces 2 White pieces have no defenders.
Python source
Rook or queen on a passed pawn's file
+4.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's rook on b8 stands behind its own passed pawn on b5, with no piece between them.
Black passed pawn No White pawn is ahead on this file or either neighboring file.
Rook behind pawn No piece stands between b8 and b5.
Python source
Protected minor piece outpost without opponent equivalent
+4.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's defended bishop on c3 is in White's half and not attacked by a White pawn. White has no knight or bishop meeting the same conditions.
Supported advance c3 is defended.
Support Direct defenders: b5.
Python source
Quiet double-lever threat machine
+4.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has 2 quiet double-attack moves, versus 0 for Black. Rd6 attacks the knight on c6 and the rook on d8.
Move The rook moves from d1 to d6: Rd6.
Fork targets After the move, the rook attacks the knight on c6 and the rook on d8.
Defenders after the move These pieces defend the destination d6 after the move.
Python source
Protected central wedge pawn beyond the midline
+4.6
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's central pawn has crossed the midline and is backed by another pawn.
Advanced pawn The pawn on e4 is on its 5th rank.
Pawn support These friendly pieces defend the advanced pawn.
Python source
Seventh-rank invasion lever
+4.4
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has safe heavy-piece entries onto the enemy's second rank, creating threats along that rank.
White entry pieces Rooks or queens with an entry to the opponent's second rank.
White landing squares Safe invasion squares counted by the motif.
Black entry pieces Rooks or queens with an entry to the opponent's second rank.
Black landing squares Safe invasion squares counted by the motif.
Python source
Heavy file pressure on an isolated or doubled enemy pawn
+4.4
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's heavy piece attacks the isolated pawn on e6 along a file with no White pawn.
Pawn target Black's pawn on e6.
Direct attackers These pieces attack the pawn.
Python source
Open invasion routes into the enemy camp
+4.4
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's queen on e6 can move to e1, an empty square in White's camp that no White piece currently attacks.
Invading piece Black's queen on e6.
Entry square Empty square e1.
Python source
Enemy pawn over-extended into our camp
+4.4
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
White's pawn on d5 is attacked by Black's queen on d7 and has no neighboring pawn support. Black controls its advance square d6 more strongly.
Weak pawn White's pawn on d5 has no neighboring pawn support.
Attackers Black's queen on d7 attacks d5.
Blocked advance d6 is more strongly controlled by Black.
Python source
Piling up on a pinned or x-rayed enemy piece
+4.4
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's bishop on f4 attacks Black's knight on d6, with Black's king on c7 behind it on the same line.
Attacking pieces White's bishop on f4.
Pinned or x-rayed target Black's knight on d6.
Piece behind it Black's king on c7.
Python source
Aligned slider, friendly piece and enemy target
+4.2
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's rook, friendly bishop, and the enemy rook line up. Other pieces still block the line.
Aligned pieces The rook on h1, bishop on h3, and enemy rook on h8 share a line.
Other blockers These pieces also block the line, so moving the highlighted friendly piece does not open a direct attack.
Python source
Cocked discovery: own screen masks a loaded slider
+4.2
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's rook on c1 lines up with Black's bishop on c8. The friendly queen on c7 blocks the attack.
Rear piece The rook on c1 points toward the two pieces on this line.
Screen The queen on c7 blocks the line to c8.
Target behind the screen The bishop on c8 lies on the same line.
Python source
Guarded minor piece prowling the enemy king ring
+4.1
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's bishop on c7 attacks 1 square beside White's king.
Attacker Black's bishop on c7.
King pressure Controls h2 beside White's king.
Support e6 and d7 defend the attacker.
Python source
Pressure on a pawn with a controlled advance
+4.1
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White pressures the pawn on c6, which stands ahead of its neighbors and has a more strongly controlled next square.
Pawn target Black's pawn on c6.
Direct attackers These pieces attack the pawn.
Neighboring pawns The target stands farther forward than these pawns.
Controlled next square The pawn's next square is empty and more strongly controlled by opposing non-king pieces.
Python source
Major piece on a semi-open file next to the enemy king
+4.0
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
The d-file has no White pawn, but d5 blocks the line from the rook on d1 to Black's king.
Major piece White's rook on d1 occupies the d-file, which has no friendly pawns.
Enemy king Black's king is on the same file.
Pieces blocking the line d5 stands between the rook or queen and the king.
Python source
Enemy minors still parked on their starting squares
+4.0
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
Black has 2 knights or bishops on original minor-piece squares, compared with 0 for White.
Black home minors 2 knights or bishops remain on the original minor-piece squares.
Python source
Pawn-protected piece superiority
+3.9
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has more pawn-protected pieces: 2 versus 0 for Black.
White pawn-protected pieces Counted pawn-protected pieces: 2.
Python source
Opponent burdened with two different kinds of weakness
+3.8
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
White has two weaknesses: a backward pawn and an exposed king.
Backward pawn White's pawns on d4 and e5 show the lagging pawn and its advanced neighbor.
Exposed king White's king on e1 has no nearby pawn shelter.
Python source
Knight pressure on the enemy king ring
+3.8
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's knight on e5 attacks 1 square beside Black's king.
Attacker White's knight on e5.
King pressure Controls g6 beside Black's king.
Python source
Advanced-pawn lead
+3.8
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's leading pawns have reached their fifth rank; Black's have reached only their second rank.
White leading pawns These pawns have reached their fifth rank, counted from their own side.
Black leading pawns These pawns have reached their second rank, counted from their own side.
Python source
Covered pawn wall against defenseless enemy pawns
+3.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has fewer completely undefended pawns than White, giving its pawn wall better support.
Black undefended pawns Pawns with no friendly defender.
White undefended pawns Pawns with no friendly defender.
Python source
Piece development lead
+3.7
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black has 4 pieces off their starting squares; White has 1.
Black developed pieces 4 pieces away from their usual starting squares.
White developed pieces 1 piece away from their usual starting squares.
Python source
Safe defended pressure on king flight squares
+3.6
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's defended pieces attack 2 squares beside White's king. No enemy pawn currently attacks these pieces.
Defended attackers Each attacker is defended and is not currently attacked by an enemy pawn.
Controlled king-neighbour squares 2 squares beside the enemy king are controlled.
Enemy king The controlled squares lie next to this king.
Python source
Favorable piece imbalance without a material lead
+3.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has 1 extra knight and 1 extra bishop versus Black's 1 extra pawn and 1 extra rook. At these values (pawn = 1, knight = 3, bishop = 3, and rook = 5), material is exactly equal.
White material White's rook on a1, White's pawns on a2, b2, h2, d3, g3, c4, and f4, White's knights on g2 and c3, and White's bishop on e3.
Black material Black's pawns on a5, e5, f5, b6, d6, c7, g7, and h7, Black's knight on c5, and Black's rooks on e8 and f8.
Python source
Profitable target pressure differential
+3.6
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has favorable exchange pressure on a bishop, while Black's corresponding target is a pawn.
White profitable targets Bishop on e7: favorable capture-and-recapture balance.
Black profitable targets Pawn on d3: favorable capture-and-recapture balance.
Python source
Checking capture
+3.5
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black can capture with Rxd1+ and give check at the same time.
Move Black can play Rxd1+: d4 to d1.
Targets Attacked after the move: king on e1.
Python source
Unopposed bishop attacking an enemy piece
+3.5
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's bishop on e3 attacks the highlighted dark squares. Black has no bishop on that square color.
Active bishop The bishop on e3 reaches into the enemy camp.
Bishop's reach Squares reached on this bishop's diagonals.
Python source
Unopposed bishop and squares without enemy pawn cover
+3.4
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White's bishop has no opposing counterpart on its square color. Its highlighted targets and occupied weak squares lack current enemy pawn cover.
Unopposed bishop White's bishop on b2 has no opposing bishop on the same square color.
Occupied weak squares White's pawns on b4 and d6 occupy squares not currently attacked by enemy pawns.
Bishop-controlled squares The bishop attacks d4 and e5; enemy pawns do not currently attack these squares.
Python source
Central-file heavy piece without contest
+3.4
White to move
8
7
6
5
4
3
2
1a
b
c
d
e
f
g
h
White has a rook or queen on a central file; Black has neither on those files.
Central heavy pieces d4 occupies the d- or e-file.
Python source
Quiet royal check with king-space edge
+3.2
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
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b
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After Ng3+ without a capture, White's king has 1 legal move; Black's king has 2 before the check.
Checking move Black can play Ng3+ without capturing.
White king 1 legal king reply after the check.
Black king 2 legal king moves before the check.
Python source
Heavy piece on an advanced pawn’s file
+3.2
White to move
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White's rook on d1 shares a file with its pawn on d6 in Black's half.
Heavy pieces Rooks or queens sharing the advanced pawns' files.
Advanced pawns Pawns already across the middle of the board.
Python source
Central cramping pawn bind freezing the enemy centre
+3.2
White to move
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White's pawn blocks an enemy pawn head-on, with a friendly pawn supporting the bind.
Advanced pawn The pawn on d5 is on its 5th rank.
Pawn support These friendly pieces defend the advanced pawn.
Blocked enemy pawn This enemy pawn is directly in front and cannot advance.
Python source
True material edge hidden without a visible lead
+3.1
Black to move
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Black has 1 extra rook versus White's 1 extra pawn and 1 extra knight. At these values (pawn = 1, knight = 3.2, and rook = 5), Black's net edge is worth 0.8 pawns.
Black material Black's pawns on c5, a7, f7, g7, and h7 and Black's rooks on a6 and f8.
White material White's rook on a1, White's pawns on a2, b2, f2, h2, g3, and c4, and White's knight on c3.
Python source
Immediate pawn cover with king-zone pressure
+3.1
Black to move
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Black has 2 pawns directly shielding its king, versus 1 for White. Its rook on e8 also attacks the enemy king's immediate neighbourhood.
Black immediate pawn cover 2 pawns on the rank directly ahead of the king, on its file or a neighbouring file.
White immediate pawn cover 1 pawn on the rank directly ahead of the king, on its file or a neighbouring file.
Attacking major piece The rook on e8 attacks e2 and e3 in the opposing king's immediate neighbourhood.
Attacked king-zone squares Squares reached directly by the highlighted major piece.
Python source
Pawn-defended attacker near enemy king
+3.1
White to move
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White's queen on b3 attacks 2 squares beside Black's king.
Attacker White's queen on b3.
King pressure Controls b7 and b8 beside Black's king.
Support a2 and c2 defend the attacker.
Python source
Minor-piece check with a second target
+3.0
Black to move
1
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Black can play Nf4+, attacking 2 targets at once.
Move Black can play Nf4+: d5 to f4.
Targets The checked king and 1 other target: bishop on e2 and king on g2.
Support The moved piece is defended by f8.
Python source
Heavy-piece defended pawn advance into opponent half
+3.0
White to move
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White can play h5, moving its pawn into Black's half. The rook on h1 defends it after the move.
Pawn advance White can play h5 into the enemy half.
Heavy-piece support h1 defends the pawn after it advances.
Python source
Limited opposing queen reach
+3.0
White to move
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Black's queen has only 3 unattacked destinations along its lines.
Restricted queen The queen on e7 has 3 destinations that are neither friendly-occupied nor attacked by White.
Unattacked destinations The remaining destinations along the queen's lines that are not attacked.
Python source
Exclusive pawn breakthrough superiority
+3.0
White to move
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White can create a passed pawn with d5. A passed pawn has no enemy pawn ahead on its file or either neighboring file.
Breakthrough move d5: d4 to d5. After this move, an additional pawn has no enemy pawn ahead on its file or either neighboring file.
Python source
Artillery-loaded pawn break
+2.9
White to move
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White can play d5, advancing into the enemy half with a rook or queen behind it. The destination has no enemy pawn attack and is not outnumbered by attackers.
Move White can play d5: d4 to d5.
Backing heavy piece The rook on d1 stands behind the pawn.
Python source
Queen check with a side target
+2.9
Black to move
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Black can play Qxf2+, attacking 4 targets at once.
Move Black can play Qxf2+: f6 to f2.
Targets The checked king and 3 other targets: rook on e1, king on g1, pawn on b2 and queen on g3.
Python source
One-way pawn power: deep breach, riding passer or rolling phalanx
+2.9
Black to move
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Black's advanced pawn stands farther forward than the enemy pawn front.
Advanced pawns Pawns holding space in enemy territory.
Pawn support Pawns supporting that advanced foothold.
Python source
Supported slider line toward the enemy king
+2.8
Black to move
1
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Black's rook on f8 lines up behind the bishop on f5 toward f2 beside White's king.
Rear slider The rook on f8 stands behind the front piece.
Front piece The bishop on f5 is the friendly piece on this line.
King-zone endpoint The line continues toward f2 beside the king on g1.
Python source
Sustained pressure on defended enemy units
+2.8
White to move
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Black's pawn on f7 is defended but remains under pressure: 2 attackers outnumber its 1 defender.
Attacking pieces White's queen on b3 and White's knight on e5.
Pressure target Black's pawn on f7.
Defenders Black's queen on e7.
Python source
Pawn storm against the castled enemy king
+2.8
White to move
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White's pawns on g4 and f5 stand within two files of Black's king on g8.
Pawn storm White's pawn on g4 and White's pawn on f5.
King shelter Black's pawn on f6, Black's pawn on f7, and Black's king on g8.
Python source
Castling rights lead
+2.8
Black to move
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Black retains both castling rights; White retains no castling rights.
Black castling rights Kingside, queenside.
White castling rights No castling rights remain.
Python source
Stacked major pieces on a file without friendly pawns
+2.8
Black to move
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Black's rook on e8 and queen on e6 share the e-file with no friendly pawn in it.
Stacked major pieces The rook on e8 and queen on e6 share a clear file.
File without friendly pawns The e-file contains no Black pawn.
Enemy king The stacked file is 2 files from the king's file.
Python source
Attacked squares around the enemy king
+2.8
Black to move
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Black attacks 4 squares beside White's king. g1 is the only empty, unattacked neighbouring square.
Attacking pieces These pieces attack the highlighted squares beside the king.
Attacked neighbouring squares 4 neighbouring squares are attacked.
Enemy king White's king is on f2.
Empty, unattacked neighbours These squares are empty and unattacked in the current position.
Python source
Home-rank king without castling rights and with little pawn cover
+2.7
White to move
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Black's king is stranded near the center with no castling rights. White's king has left its home central files.
White king This king is already away from its home central files.
Black stranded king This king remains on its home central files with no castling rights.
Remaining enemy shelter Only 2 shield pawns remain on the nearby files and first two pawn ranks.
Python source
Protected minor attack on a pawn-uncovered enemy piece
+2.7
Black to move
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Black's knight on f6 attacks White's pawn on e4. A friendly pawn defends the attacker; no White pawn defends the target.
Attacking piece Black's knight on f6.
Targets It attacks e4.
Support The attacker is defended by g7.
Python source
More permanent cracks in the enemy camp
+2.7
Black to move
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White's camp has more persistent weaknesses than Black's. Each color shows one counted kind of weakness.
White restricted minors Rim knights or bishops with very short diagonals.
White vulnerable pawns Attacked pawn defects without a pawn defender.
Black vulnerable pawns Attacked pawn defects without a pawn defender.
Python source
More non-pawn pieces or a forcing check
+2.6
Black to move
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Black has 4 non-pawn pieces; White has 3. This motif counts pieces equally, rather than by their material value.
Black bishops 2 bishops: d6 and e6.
Black rook 1 rook: b8.
White rooks 2 rooks: d1 and e1.
Python source
Advanced knight harassing enemy pieces
+2.6
Black to move
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Black's knight on e3 attacks White's pawn on g2. The knight stands in White's half.
Attacking piece Black's knight on e3.
Targets It attacks g2.
Python source
Protected advanced piece hitting an enemy pawn
+2.6
White to move
8
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White's knight on g5 attacks Black's pawn on f7 and pawn on h7. The attacker is defended and stands in Black's half.
Attacking piece White's knight on g5.
Targets It attacks f7 and h7.
Support The attacker is defended by f4.
Python source
Enemy royals already netted
+2.6
Black to move
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Black can play Bh4+, checking from a square near the enemy king that no enemy piece currently attacks.
Move The bishop moves from f6 to h4: Bh4+.
Checked king The move checks the king on f2.
Python source
One-move discovered attack on queen, rook, or king
+2.6
White to move
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White's pawn on f4 is the only piece between its rook on f1 and Black's queen on f7. The blocker has legal moves, but none uncovers this attack.
Rear attacker White's rook on f1.
Friendly screen f4 is the only piece between the highlighted endpoints.
X-ray target The aligned enemy piece is Black's queen on f7.
Python source
Enemy camp riddled with concrete pressure points
+2.6
White to move
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White has 2 attackers against Black's pawn on g5, versus 1 defender.
Weak pawn Black's pawn on g5 is the target.
Attackers White's bishop on c1 and White's pawn on h4 attack g5.
Defender Black's pawn on h6 defends g5.
Python source
Castling rights against a home-rank king without them
+2.5
White to move
8
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Black's king is stranded near the center with no castling rights. White still retains castling rights.
White king This side retains castling rights.
Black stranded king This king remains on its home central files with no castling rights.
Undeveloped enemy minors These knights or bishops still occupy their starting squares.
Python source
Deep enemy piece outnumbered in our camp
+2.4
Black to move
1
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White's pawn on d5 stands in Black's half with 2 Black attackers and 1 White defender.
Invading targets d5 lies in Black's half, with more attackers than defenders.
Attackers The friendly force pressuring the invaders.
Defenders Defenders of the invading target: queen on d3.
Python source
Blockaded pawn under heavy-piece pressure
+2.4
White to move
8
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White blockades and attacks the pawn on h6 along its file. The pawn has no pawn defender.
Pawn target Black's pawn on h6.
Direct attackers These pieces attack the pawn.
Blockader This piece occupies the pawn's next square.
Python source
Overloaded enemy defender with two attacked wards
+2.4
White to move
8
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Black's queen on d8 defends d5 and c8, and White attacks each target.
Shared defender This piece defends both marked targets.
Target on d5 The pawn on d5 is attacked and has 2 defenders, including the shared defender.
Target on c8 The rook on c8 is attacked and has only this defender.
Attacking pieces These pieces attack the marked targets.
Python source
Pawn-led material ambush and knight fork geometry
+2.4
Black to move
1
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Black can play Ng3+: the knight checks the king and attacks the rook on f1 and the queen on e2.
Move The knight moves from h5 to g3: Ng3+.
Fork targets After the move, the knight attacks the rook on f1 and the queen on e2.
Checked king The move checks the king on h1.
Python source
Screened slider aimed at a king-side or major-piece target
+2.4
Black to move
1
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Black's bishop on f5 screens the rook on f8 from the pawn on f2 beside White's king.
Rear rook Black's rook on f8 stands behind the front piece.
Front bishop The bishop on f5 blocks the rear piece's line.
King-shield target The pawn on f2 stands beside White's king on g1.
Python source
Enemy pieces pinned under our slider x-ray
+2.4
White to move
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White's queen on f3 pins the bishop on f6 to the king on f8. Moving it off this line would expose the king to check.
Pinned piece The piece on f6 shields its king.
Pinning piece Moving the pinned piece off this line would expose its king.
King behind it The king on f8 is behind the pinned piece.
Python source
One sided pressure on chronically weak enemy pawns
+2.4
Black to move
1
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White has more isolated pawns or pawn fronts without rear pawn support. Black outnumbers the defenders of d4.
Pawn target White's pawn on d4.
Direct attackers These pieces attack the pawn.
Python source
Aligned slider battery
+2.3
White to move
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White has two bishops, rooks or queens aligned on a rank, file or diagonal with no piece between them. Black has no such pair; the count does not check whether the pieces defend each other.
Aligned battery a1 and f1 share clear lines.
Python source
Overloaded enemy defender stretched across two falling targets
+2.3
Black to move
1
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a
White's queen on d1 defends c2 and g4, and Black attacks each target.
Shared defender This piece defends both marked targets.
Target on c2 The pawn on c2 is attacked and has only this defender.
Target on g4 The pawn on g4 is attacked and has only this defender.
Attacking pieces These pieces attack the marked targets.
Python source
Loaded battery aimed at the enemy camp
+2.3
White to move
8
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White's rook on f4 attacks Black's pawn on f7, with the rook on f1 behind it.
Front attacker The rook on f4 attacks f7 directly.
Rear piece The rook on f1 shares a clear line with the front attacker.
Enemy target Black's pawn on f7 is the first piece beyond the attacker.
Python source
Quiet discovered attack unveiling a rear slider onto valuable prey
+2.3
White to move
8
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White can play Bb6: the bishop attacks the queen on c7, while the move opens the rook's attack on the bishop on e6.
Move The bishop moves from e3 to b6: Bb6.
New attack After the move, the bishop attacks the queen on c7.
Opened line Moving the bishop opens e1 to e6.
Python source
Knight one move from a sealed deep outpost
+2.2
White to move
8
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White can play Nd5 to a pawn-supported post, with 2 defenders against 1 attackers. No enemy pawn is ahead on either neighboring file.
Move White can play Nd5: c3 to d5.
Pawn support These pawns defend the knight after it lands.
Destination attackers Enemy pieces attacking the knight's destination.
Python source
One-way durable king-pin pressure on enemy officers
+2.2
White to move
8
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White's queen on f3 pins the bishop on f6 to the king on f8. Moving it off this line would expose the king to check.
Pinned piece The piece on f6 shields its king.
Pinning piece Moving the pinned piece off this line would expose its king.
King behind it The king on f8 is behind the pinned piece.
Python source
Overloaded sole enemy defender under dual pressure
+2.2
White to move
8
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Black's bishop on b6 defends c5 and a7, and White attacks each target.
Shared defender The only non-king defender of the marked targets.
Target on c5 The pawn on c5 is attacked and has only this defender.
Target on a7 The pawn on a7 is attacked and has only this defender.
Attacking pieces These pieces attack the marked targets.
Python source
Loaded discovery lines behind own pieces
+2.2
White to move
8
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1a
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White's pawn on d4 can capture on c5, letting White's rook on d3 attack Black's rook on d6.
Hidden slider White's rook on d3.
Move aside White's pawn on d4 and Black's pawn on c5.
Discovered target Black's rook on d6.
Python source
Enemy pieces idling behind their own lines
+2.2
White to move
8
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1a
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c
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Black's highlighted pieces stay in their own half, attacking no enemy unit and defending no attacked friendly unit. Each attacks at most one square in the enemy half outside enemy pawn control.
Black idle pieces Black's knight on a6 and Black's bishop on g7.
Python source
Outside queenside pawn majority with castled kings
+2.1
White to move
8
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h
White has a 3–2 pawn majority on the queenside.
White queenside 3 pawns on this wing.
Black queenside 2 pawns on this wing.
White king and shelter Both kings are on the kingside; these pawns shelter the friendly king.
Black king and shelter The opposing king is on the kingside.
Python source
One-way material-winning pressure board
+2.1
Black to move
1
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b
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Black can play Nb4: the knight attacks the queen on c2 and the bishop on d3.
Move The knight moves from c6 to b4: Nb4.
Fork targets After the move, the knight attacks the queen on c2 and the bishop on d3.
Defenders after the move These pieces defend the destination b4 after the move.
Python source
One-sided crossfire on enemy pieces and free pawns
+2.1
Black to move
1
2
3
4
5
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7
8h
g
f
e
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b
a
Black puts pressure on more enemy targets than White does: 2 against 0.
Black targets Enemy pawns or pieces attacked by the other side.
Python source
Checking moves from two pieces
+2.0
Black to move
1
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8h
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b
a
Black can give check with 2 different pieces: a rook and a queen. The colors show one option for each piece.
Queen check Qe3+: d4 to e3.
Rook check Rc1+: c8 to c1.
Checked king Both pieces have a move that checks the king on e1.
Python source
Restricted or exposed enemy pieces
+2.0
White to move
8
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Black's highlighted piece has no empty or enemy-occupied attack destination that passes this motif's safety test. This compares attacked squares, not legal moves.
Restricted piece Black's bishop on f8 has no empty or enemy-occupied attack destination that passes the motif's safety test.
Python source
Ready demolition capture against the enemy king shelter
+2.0
White to move
8
7
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1a
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g
h
White can play Nxf5+, removing a pawn near Black's king and giving check.
Move The knight moves from h4 to f5: Nxf5+.
Captured piece The pawn on f5 is captured.
Checked king The move checks the king on g7.
Python source
Healthy wing pawn majority away from the enemy king
+2.0
White to move
8
7
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1a
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h
White has 2 queenside pawns against Black's 1, on more files. At least one has an empty forward square with as many friendly defenders as enemy attackers.
White majority White's pawn on a2 and White's pawn on b3.
Black pawns on this wing Black's pawn on a5.
Python source
Major piece dominates the squares next to the enemy king
+1.9
White to move
8
7
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1a
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h
White's queen on h6 attacks 3 squares beside Black's king.
Attacker White's queen on h6.
King pressure Controls g7, h7 and h8 beside Black's king.
Python source
Net piece-to-piece pressure surplus
+1.9
Black to move
1
2
3
4
5
6
7
8h
g
f
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c
b
a
Black puts pressure on more enemy targets than White does: 2 against 0.
Black targets Enemy pawns or pieces attacked by the other side.
Python source
Safe pawn grab advantage
+1.9
White to move
8
7
6
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h
White has 1 pawn capture that leaves the capturing pawn unattacked, versus 0 for Black. cxd5 takes the pawn on d5.
Move The pawn moves from c4 to d5: cxd5.
Captured piece The pawn on d5 is captured.
Python source
Central queen against a king that has lost castling rights
+1.9
White to move
8
7
6
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1a
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c
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e
f
g
h
White's queen on c5 is in the central sixteen squares. Black has no castling rights.
Central queen c5 is in the central sixteen squares.
Enemy king No castling rights remain.
Python source
Tempo-gaining threat creation dominance
+1.8
Black to move
1
2
3
4
5
6
7
8h
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f
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c
b
a
Black's queen on d8 can move to c7, safely creating an attack on White's bishop on c6, which was not attacked before.
Key pieces Black's queen on d8.
Targets White's bishop on c6.
Move or pressure square c7.
Python source
Enemy queen nailed to lone defense
+1.8
White to move
8
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5
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1a
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c
d
e
f
g
h
Black's queen is tied to defending an attacked pawn or minor piece.
Target The pawn or minor on f7 depends on the queen's protection.
Only defenders Only enemy queens defend this target.
Pressure Pieces applying pressure to the target.
Python source
Heavy-piece pressure on a lightly defended pawn
+1.8
White to move
8
7
6
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1a
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c
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e
f
g
h
White's rook or queen attacks the pawn on e6 along a file with no friendly pawn. The target has no pawn defender and at most one other defender.
Pawn target Black's pawn on e6.
Direct attackers These pieces attack the pawn.
Pawn defenders The target has at most one defender, and none is a pawn.
Python source
Deep conversion asset: seventh-rank heavy or connected passers
+1.7
White to move
8
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White's queen on h7 has reached the enemy's last three ranks, attacking g6 and f7.
Invading heavy piece The queen on h7 is inside enemy territory.
Enemy targets Pieces attacked by the invader.
Python source
Opposite wing pawn storm with a shielded home king
+1.7
White to move
8
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The kings are on opposite wings, and White has a pawn storm aimed at the enemy king.
Pawn storm Pawns on the enemy king's wing.
Enemy king The king on c7 faces this pawn storm.
Own king The king on h2 is on the other wing.
Python source
Screened slider line toward the enemy king
+1.7
White to move
8
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The knight on d5 blocks White's queen on b3 from g8 beside Black's king.
Rear queen White's queen on b3 stands behind the front piece.
Front knight The knight on d5 blocks the rear piece's line.
King-zone endpoint The line reaches g8 beside the king on h8.
Python source
Slider battery aimed at an enemy piece
+1.7
Black to move
1
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Black's queen on d4 attacks White's pawn on b2, backed by the bishop on g7.
Front attacker The queen on d4 directly attacks b2.
Supporting slider The bishop on g7 defends the front attacker along the same line.
Enemy target White's pawn on b2 is the first enemy piece beyond the front attacker.
Python source
Queen mobility edge
+1.7
Black to move
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Black's queen has more legal destinations: 16 versus 9.
Black queen The queen whose mobility is compared.
Black queen destinations 16 legal destination squares.
White queen The queen whose mobility is compared.
White queen destinations 9 legal destination squares.
Python source
Heavy siege on a frozen lone pawn on a half-open file
+1.7
Black to move
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b
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Black's heavy-piece attack outnumbers the pawn's defenders, while the pawn on h3 cannot push into a clear, pawn-unattacked square.
Pawn target White's pawn on h3.
Direct attackers These pieces attack the pawn.
Stopped advance The pawn's next square is occupied or attacked by an opposing pawn.
Python source
Fianchettoed bishop support
+1.7
White to move
8
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White's bishops sit one square behind their b- or g-file pawns.
Fianchetto Bishop on g2, behind the pawn on g3.
Fianchetto Bishop on b2, behind the pawn on b3.
Python source
Invasion piece on the seventh rank
+1.6
White to move
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White's bishop on a7 stands one rank before Black's back rank.
Seventh-rank invaders a7 has reached the rank just before the enemy back rank.
Python source
Overloaded defender facing scattered attacks
+1.6
White to move
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Black's queen on d6 defends both its knight on c5 and pawn on e6. Different White pieces attack the two targets.
Attacked targets c5 and e6 are attacked by different friendly pieces.
Shared defender d6 defends both targets; other defenders may exist.
Attackers b4 and d4 attack the two targets.
Python source
Home-rank pressure or a second-rank major piece
+1.6
White to move
8
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White's rook on c7 occupies Black's second rank.
Second-rank major piece White's rook on c7 occupies Black's second rank.
Python source
Ready discovered-attack x-ray on an enemy heavy piece
+1.5
Black to move
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Black's queen on f5 lines up with White's queen on d5. The friendly pawn on e5 blocks the attack.
Rear piece The queen on f5 points toward the two pieces on this line.
Screen The pawn on e5 blocks the line to d5.
Target behind the screen The queen on d5 lies on the same line.
Python source
Pinned-and-hanging with armed royal forks
+1.5
White to move
8
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White can play Ne6: the knight attacks the queen on d8 and the rook on f8.
Move The knight moves from c7 to e6: Ne6.
Fork targets After the move, the knight attacks the queen on d8 and the rook on f8.
Defenders after the move These pieces defend the destination e6 after the move.
Python source
Rear-rank piece pressure edge
+1.5
White to move
8
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White attacks more pieces on the enemy back rank: 1 versus 0.
White attacked back-rank pieces Counted attacked back-rank pieces: 1.
Python source
Clean undoubled pawns while opponent is doubled
+1.5
White to move
8
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White has no doubled pawns; Black does.
Doubled enemy pawns f6 and f7 share files.
Undoubled friendly pawns Every friendly pawn occupies a different file.
Python source
Unopposed long-diagonal bishop aimed at the enemy king
+1.5
Black to move
1
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Black's bishop on c6 attacks 1 square beside White's king.
Attacker Black's bishop on c6.
King pressure Controls f3 beside White's king.
Python source
Heavy-piece geometry on the enemy first two ranks
+1.5
White to move
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White's queen on h7 has reached the enemy's last three ranks, attacking g6 and f7.
Invading heavy piece The queen on h7 is inside enemy territory.
Enemy targets Pieces attacked by the invader.
Python source
Advanced pawn option edge
+1.5
White to move
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White has 3 legal pawn moves ending in Black's half; Black has 1 ending in White's half.
White advance options 3 moves into enemy territory: hxg6, h6, d5.
Black advance options 1 move into enemy territory: a3.
Python source
Connected promotion ladder passers
+1.5
White to move
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White's protected passed pawn is close to promotion, with no enemy pawn left ahead of it.
Near-promotion passer The pawn on d6 is at most two pushes from promotion.
Support Friendly pieces support the advanced pawn.
Python source
Far advanced pawn in opponent half
+1.5
White to move
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White's pawn on h6 is 2 ranks from promotion. This is a rank distance, not a guarantee of a clear advance.
Far-advanced pawns h6 is on the sixth rank or beyond.
Python source
Queen-rook file coordination edge
+1.4
White to move
8
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White's queen on a4 and rook on a1 share a file; Black has no such pair. Sharing a file does not by itself mean they defend each other.
Queen and rook a1 and a4: share a file.
Black heavy pieces No opposing queen and rook share a file.
Intervening pieces Pieces between the queen and rook: pawn on a2.
Python source
Connected queen-rook battery versus unconnected enemy heavies
+1.4
White to move
8
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White's queen on f3 defends its rook on e3. No Black rook or queen defends another rook or queen.
Queen and rook e3 and f3: the queen defends the rook.
Black heavy pieces No opposing rook or queen defends another rook or queen.
Python source
Caged counterplay: lone queen sway or blockaded passing lane
+1.4
Black to move
1
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Each White passed pawn has a specific obstacle: a blockade, direct pressure, or control of its advance or promotion square.
Enemy passed pawns These pawns have no opposing pawn ahead on their own or neighboring files.
Blockader This defended non-king piece occupies the passer's next square.
Python source
Minor-piece fork resource on enemy minor pieces
+1.3
White to move
8
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White can play Bf3, attacking 2 targets at once.
Move White can play Bf3: e2 to f3.
Targets Attacked after the move: knight on g4 and knight on c6.
Python source
Heavy piece aligned with enemy king
+1.3
White to move
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White's queen on e2 shares a file with Black's king on e8. Intervening pieces block a direct attack.
Aligned heavy pieces e2 shares a rank or file with the enemy king.
Enemy king The king shares a rank or file with the highlighted heavy piece.
Intervening pieces These pieces block the line: knight on e4 and pawn on e6.
Python source
Enemy minor marooned in our camp
+1.3
Black to move
1
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White's piece is hemmed in: its available exits are tightly controlled.
Restricted enemy piece The piece on g2 has very little safe room.
Controlled exits The piece's empty exit squares are covered or restricted.
Python source
One-move-away covered fork on enemy heavy pieces
+1.3
White to move
8
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White can play Nc6: the knight attacks the queen on e7 and the rook on d8.
Move The knight moves from e5 to c6: Nc6.
Fork targets After the move, the knight attacks the queen on e7 and the rook on d8.
Defenders after the move These pieces defend the destination c6 after the move.
Python source
Healthy pawn-break monopoly
+1.3
White to move
8
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White can play f4, reaching relative rank 4, with no enemy pawn attack and at least as many defenders as attackers. Black has no comparable pawn push.
Move White can play f4: f3 to f4.
Destination defenders Friendly pieces defending the pawn after the push.
Python source
Pawn persecution of enemy minors
+1.3
White to move
8
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White has more pawn-pressure opportunities against enemy knights and bishops, including immediate pawn advances.
White pawn pressure Pawns already attacking minors or ready to advance against them.
White advance squares A pawn advance to these squares attacks a minor piece.
White minor-piece targets Knights or bishops affected by the pawn pressure.
Python source
Safe rook fork on two enemy units
+1.3
White to move
8
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White can play Rd7, attacking 2 targets at once.
Move White can play Rd7: c7 to d7.
Targets Attacked after the move: bishop on b7 and bishop on e7.
Python source
Open slider lines drilling into the castled enemy king
+1.2
White to move
8
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White has 2 bishops, rooks or queens aligned toward squares beside Black's king, versus 0 in return. The count excludes pawn-blocked lines but can include lines blocked by other pieces.
Aimed sliders White's bishop on g2 and White's bishop on f4.
King-zone endpoints Squares beside the king where the counted lines lead; non-pawn blockers may remain.
Python source
Heavy-piece battery or second-rank foothold
+1.2
White to move
8
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White's rook on b7 occupies Black's second rank, which still contains 3 Black pawns.
Second-rank major piece The rook on b7 occupies the enemy's second rank.
Enemy pawns on that rank 3 Black pawns remain on the same rank.
Python source
Protected central bishop with forward range
+1.1
White to move
8
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White's defended bishop on d4 attacks 6 squares in Black's half. These are attacked squares, not necessarily legal moves.
Central bishop d4 is defended.
Support Direct defenders: d1 and c3.
Targets Attacked squares: c5, e5, b6, f6, a7 and g7.
Python source
Home-rank king sealed and netted
+1.1
Black to move
1
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8h
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a
Black can play Qe1+, leaving the checked king no king move and at most three legal replies.
Move The queen moves from e3 to e1: Qe1+.
Checked king The move checks the king on g1.
Python source
Masked slider battery aimed at the enemy king
+1.1
Black to move
1
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8h
g
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b
a
Black's pawn on d5 is the only piece between its queen on c6 and White's king on g2. The count checks alignment, not whether a legal move can uncover check.
Rear attacker Black's queen on c6.
Friendly screen d5 is the only piece between the highlighted endpoints.
X-ray target The aligned enemy piece is White's king on g2.
Python source
Enemy piece defended only by king
+1.1
White to move
8
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White attacks Black's queen on e7, whose only defender is the king on f8.
Attacked pieces e7 depends only on the king for defence.
Sole defender The king is the only defender of the highlighted material.
Attackers c7 applies the pressure.
Python source
Safe minor-piece double attack
+1.1
White to move
8
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White can play Ng6, attacking 2 targets at once.
Move White can play Ng6: e5 to g6.
Targets Attacked after the move: bishop on e7 and rook on h8.
Python source
Safe double attack available in one move
+1.1
White to move
8
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White's bishop on c5 can move to e7, attacking 3 valuable targets at once.
Forking move White's bishop on c5 and Empty square e7.
Simultaneous targets Black's bishop on h4, Black's rook on d8, and Black's rook on f8.
Python source
Safe invader entrenched on the enemy pawn rank
+1.1
Black to move
1
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3
4
5
6
7
8h
g
f
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b
a
Black can play Rb2, which attacks the pawn on a2 and the pawn on f2.
Move The rook moves from b8 to b2: Rb2.
New attack After the move, the rook attacks the pawn on a2 and the pawn on f2.
Python source
Safe advanced passed pawn poised to promote
+1.1
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's passed pawn has an empty square ahead. Both squares have at least as many defenders as attackers.
Advanced pawn The pawn on c4 is on its 5th rank.
Support These friendly pieces defend the advanced pawn.
Clear next square The passer's next square is empty and not over-attacked.
Python source
Loaded queen battery aimed down the line at the enemy camp
+1.0
Black to move
1
2
3
4
5
6
7
8h
g
f
e
d
c
b
a
Black's pawn on e4 stands between the queen on e7 and White's queen on e3.
Rear queen Black's queen on e7 stands behind the front piece.
Front pawn The pawn on e4 blocks the rear piece's line.
Piece beyond the front White's queen on e3 is the next piece along that line.
Python source

Material or mobility advantage

Material advantage for the side to move

Compact pawn mass against a splintered enemy skeleton

Bankable extra material with enemy counterplay muted

Undoubled pawn-file majority on a wing

Positional feature advantage

Two-file pawn bridgehead wedge or cohesive wall vs stranded pawn

More legal moves

Rook or queen on a line with no enemy pieces

More central squares occupied or attacked

Own king snug in an unpressured shelter

Connected frontmost pawns

Queen placement and mobility

Six-sector positional scoreboard edge

Live pawn levers versus a frozen enemy core

Broad quiet dominance scoreboard

Long-range firepower dominance

Quiet move threatens loose piece

Permanent holes in the enemy camp

One-way contact dominance over an untouched army

More rooks off their starting squares

Enemy pieces sharing a file

Rank-connected heavy piece coordination edge

Pawn storm race lead on the enemy king

Queenless king centralization edge

File-by-file pawn advance lead

One-way siege of unsupportable enemy pawns

More undefended enemy pieces than our own

Greater piece centralization

Greater non-pawn reach

Opposing minor-piece placement and reach

More opposing minor pieces on home ranks

One-way projected heavy batteries and open-file monopoly

Superior pawn structure and passed pawn edge

Unopposed bishop reaching the enemy camp

Nearest-piece proximity to the enemy king

Worst-piece breathing-room mismatch

Banked exchange or piece bounty

King breathing room mismatch

Pressure on a pawn without rear pawn support

Our pieces stand where they cannot be kicked

Enemy king stranded without shelter

Caged enemy rooks versus our deep-breaching rook

Exclusive bishop pair with no material deficit

Slider fire on the breached enemy king shield

Cashable pawn: on-the-spot pawn grab that survives the exchange sequence

One-sided artillery barrage on the enemy king zone

Piece concentration near the enemy king

Slider x-ray pressure through an enemy screen onto a heavier piece

Forcing-stroke initiative surplus

Two distant entries into a weakened enemy camp

Protected pawn leading the advance

Safe piece infiltration in enemy territory

Pawn-space edge in opponent half

Safe fresh-threat move surplus over a silenced opponent

Enemy army bottled behind the midline under our bridgehead

Pawn-supported advanced minor piece

Rooks and queens with no friendly pawn ahead

Space-gaining pawn wedge in the centre

Existing double attack by one piece

Opponent starved of forcing resources

Queen restriction or a checking edge

Mobile queen against limited opposing queen reach

Stranded enemy king or safe double strike

Passed pawn majority edge

Opponent lags in mobilization and king shelter

Pressure on weak squares around the enemy king

Slider battery reinforced and trained on the enemy king

Heavy-piece pressure on the enemy pawn rank

Free bishop against pawn-strangled enemy bishop

Discovery-fork-initiative

Knight fork of a heavy piece and another target

Ripe undefended enemy target capturable right now

Opposing rooks on their starting squares

Heavy piece raiding the enemy second rank

Pressure on the opponent weak pawns

Rook on a file without enemy pawns or major pieces

Central pawn wedge lead

Pawn majority on one or both wings

Opponent saddled with a bad minor piece