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Add SEE to move ordering (gains 44.7 +/- 22.9)

This commit is contained in:
Mattia Giambirtone 2024-05-11 11:25:45 +02:00
parent ca3f13ef04
commit 9331729d76
1 changed files with 28 additions and 23 deletions
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51
Chess/nimfish/nimfishpkg/search.nim
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@ -81,12 +81,11 @@ const
# higher offsets will always be placed
# first
TTMOVE_OFFSET = 700_000
MVV_LVA_OFFSET = 600_000
GOOD_SEE_OFFSET {.used.} = 500_000
KILLERS_OFFSET = 400_000
HISTORY_OFFSET = 300_000
QUIET_OFFSET = 200_000
BAD_SEE_OFFSET {.used.} = 100_000
GOOD_SEE_OFFSET = 600_000
KILLERS_OFFSET = 500_000
HISTORY_OFFSET = 400_000
QUIET_OFFSET = 300_000
BAD_SEE_OFFSET = 200_000
func computeLMRTable: array[MAX_DEPTH, array[218, int]] {.compileTime.} =
@ -187,7 +186,10 @@ proc getEstimatedMoveScore(self: SearchManager, move: Move, ply: int): int =
return KILLERS_OFFSET
if move.isTactical():
if move.isCapture():
let seeScore = self.board.position.see(move)
# We want to prioritize good captures (see > 0), but if the capture
# is bad then at least we sort it with MVVLVA
if seeScore < 0 and (move.isCapture() or move.isEnPassant()):
# Implementation of MVVLVA: Most Valuable Victim Least Valuable Aggressor.
# We prioritize moves that capture the most valuable pieces, and as a
# second goal we want to use our least valuable pieces to do so (this
@ -196,23 +198,26 @@ proc getEstimatedMoveScore(self: SearchManager, move: Move, ply: int): int =
let capturedScore = MVV_LVA_MULTIPLIER * self.board.position.getPieceScore(move.targetSquare)
result = capturedScore - self.board.position.getPieceScore(move.startSquare)
# If the capture is also a promotion we want to give it an even bigger bonus
if move.isPromotion():
var piece: Piece
case move.getPromotionType():
of PromoteToBishop:
piece = Piece(kind: Bishop, color: sideToMove)
of PromoteToKnight:
piece = Piece(kind: Knight, color: sideToMove)
of PromoteToRook:
piece = Piece(kind: Rook, color: sideToMove)
of PromoteToQueen:
piece = Piece(kind: Queen, color: sideToMove)
else:
discard # Unreachable
result += PROMOTION_MULTIPLIER * self.board.position.getPieceScore(piece, move.targetSquare)
# If the capture is also a promotion we want to give it an even bigger bonus
if move.isPromotion():
var piece: Piece
case move.getPromotionType():
of PromoteToBishop:
piece = Piece(kind: Bishop, color: sideToMove)
of PromoteToKnight:
piece = Piece(kind: Knight, color: sideToMove)
of PromoteToRook:
piece = Piece(kind: Rook, color: sideToMove)
of PromoteToQueen:
piece = Piece(kind: Queen, color: sideToMove)
else:
discard # Unreachable
result += PROMOTION_MULTIPLIER * self.board.position.getPieceScore(piece, move.targetSquare)
return result + MVV_LVA_OFFSET
return result + BAD_SEE_OFFSET
else:
# If the capture is good then we just use the SEE score + the offset
return seeScore + GOOD_SEE_OFFSET
if move.isQuiet():
# History heuristic bonus