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More efficient move calculation for Gaviota and Syzygy #1069

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merged 2 commits into from
Jan 9, 2025
Merged

More efficient move calculation for Gaviota and Syzygy #1069

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9fc2f61
More efficient move calculation for Gaviota and Syzygy
adbar Jan 6, 2025
89f030c
cancel changes to moves
adbar Jan 8, 2025
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44 changes: 24 additions & 20 deletions lib/engine_wrapper.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
COMMANDS_TYPE, MOVE, InfoStrDict, InfoDictKeys, InfoDictValue, GO_COMMANDS_TYPE, EGTPATH_TYPE,
ENGINE_INPUT_ARGS_TYPE, ENGINE_INPUT_KWARGS_TYPE)
from extra_game_handlers import game_specific_options
from operator import itemgetter
from typing import Any, Optional, Union, Literal, cast
from types import TracebackType
LICHESS_TYPE = Union[lichess.Lichess, test_bot.lichess.Lichess]
Expand Down Expand Up @@ -1149,8 +1150,10 @@ def get_syzygy(board: chess.Board, game: model.Game,
or chess.popcount(board.occupied) > syzygy_cfg.max_pieces
or board.uci_variant not in ["chess", "antichess", "atomic"]):
return None, -3

move: Union[chess.Move, list[chess.Move]]
move_quality = syzygy_cfg.move_quality

with chess.syzygy.open_tablebase(syzygy_cfg.paths[0]) as tablebase:
for path in syzygy_cfg.paths[1:]:
tablebase.add_directory(path)
Expand All @@ -1164,13 +1167,12 @@ def get_syzygy(board: chess.Board, game: model.Game,
move = [chess_move for chess_move, dtz in good_moves]
logger.info(f"Suggesting moves from syzygy (wdl: {best_wdl}) for game {game.id}")
return move, best_wdl
else:
# There can be multiple moves with the same dtz.
best_dtz = min([dtz for chess_move, dtz in good_moves])
best_moves = [chess_move for chess_move, dtz in good_moves if dtz == best_dtz]
move = random.choice(best_moves)
logger.info(f"Got move {move.uci()} from syzygy (wdl: {best_wdl}, dtz: {best_dtz}) for game {game.id}")
return move, best_wdl
# There can be multiple moves with the same dtz.
best_dtz = min(good_moves, key=itemgetter(1))[1]
best_moves = [chess_move for chess_move, dtz in good_moves if dtz == best_dtz]
move = random.choice(best_moves)
logger.info(f"Got move {move.uci()} from syzygy (wdl: {best_wdl}, dtz: {best_dtz}) for game {game.id}")
return move, best_wdl
except KeyError:
# Attempt to only get the WDL score. It returns moves of quality="suggest", even if quality is set to "best".
try:
Expand Down Expand Up @@ -1222,15 +1224,18 @@ def get_gaviota(board: chess.Board, game: model.Game,
or chess.popcount(board.occupied) > gaviota_cfg.max_pieces
or board.uci_variant != "chess"):
return None, -3

move: Union[chess.Move, list[chess.Move]]
move_quality = gaviota_cfg.move_quality

# Since gaviota TBs use dtm and not dtz, we have to put a limit where after it the position are considered to have
# a syzygy wdl=1/-1, so the positions are draws under the 50 move rule. We use min_dtm_to_consider_as_wdl_1 as a
# second limit, because if a position has 5 pieces and dtm=110 it may take 98 half-moves, to go down to 4 pieces and
# another 12 to mate, so this position has a syzygy wdl=2/-2. To be safe, the first limit is 100 moves, which
# guarantees that all moves have a syzygy wdl=2/-2. Setting min_dtm_to_consider_as_wdl_1 to 100 will disable it
# because dtm >= dtz, so if abs(dtm) < 100 => abs(dtz) < 100, so wdl=2/-2.
min_dtm_to_consider_as_wdl_1 = gaviota_cfg.min_dtm_to_consider_as_wdl_1

with chess.gaviota.open_tablebase(gaviota_cfg.paths[0]) as tablebase:
for path in gaviota_cfg.paths[1:]:
tablebase.add_directory(path)
Expand All @@ -1240,7 +1245,7 @@ def get_gaviota(board: chess.Board, game: model.Game,

best_wdl = max(map(dtm_to_gaviota_wdl, moves.values()))
good_moves = [(move, dtm) for move, dtm in moves.items() if dtm_to_gaviota_wdl(dtm) == best_wdl]
best_dtm = min([dtm for move, dtm in good_moves])
best_dtm = min(good_moves, key=itemgetter(1))[1]

pseudo_wdl = dtm_to_wdl(best_dtm, min_dtm_to_consider_as_wdl_1)
if move_quality == "suggest":
Expand All @@ -1249,7 +1254,7 @@ def get_gaviota(board: chess.Board, game: model.Game,
move = [chess_move for chess_move, dtm in best_moves]
logger.info(f"Suggesting moves from gaviota (pseudo wdl: {pseudo_wdl}) for game {game.id}")
else:
move, dtm = random.choice(best_moves)
move, dtm = best_moves[0]
logger.info(f"Got move {move.uci()} from gaviota (pseudo wdl: {pseudo_wdl}, dtm: {dtm})"
f" for game {game.id}")
else:
Expand Down Expand Up @@ -1295,21 +1300,20 @@ def good_enough_gaviota_moves(good_moves: list[tuple[chess.Move, int]], best_dtm
# want to avoid these positions, if there is a move where even when we add the halfmove_clock the
# dtz is still <100.
return [(move, dtm) for move, dtm in good_moves if dtm < 100]
elif best_dtm < min_dtm_to_consider_as_wdl_1:
if best_dtm < min_dtm_to_consider_as_wdl_1:
# If a move had wdl=2 and dtz=98, but halfmove_clock is 4 then the real wdl=1 and dtz=102, so we
# want to avoid these positions, if there is a move where even when we add the halfmove_clock the
# dtz is still <100.
return [(move, dtm) for move, dtm in good_moves if dtm < min_dtm_to_consider_as_wdl_1]
elif best_dtm <= -min_dtm_to_consider_as_wdl_1:
if best_dtm <= -min_dtm_to_consider_as_wdl_1:
# If a move had wdl=-2 and dtz=-98, but halfmove_clock is 4 then the real wdl=-1 and dtz=-102, so we
# want to only choose between the moves where the real wdl=-1.
return [(move, dtm) for move, dtm in good_moves if dtm <= -min_dtm_to_consider_as_wdl_1]
elif best_dtm <= -100:
if best_dtm <= -100:
# If a move had wdl=-2 and dtz=-98, but halfmove_clock is 4 then the real wdl=-1 and dtz=-102, so we
# want to only choose between the moves where the real wdl=-1.
return [(move, dtm) for move, dtm in good_moves if dtm <= -100]
else:
return good_moves
return good_moves


def piecewise_function(range_definitions: list[tuple[float, Literal["e", "i"], int]], last_value: int,
Expand Down Expand Up @@ -1366,9 +1370,9 @@ def score_syzygy_moves(board: chess.Board,
"""Score all the moves using syzygy egtbs."""
moves = {}
for move in board.legal_moves:
board_copy = board.copy()
board_copy.push(move)
moves[move] = scorer(tablebase, board_copy)
board.push(move)
moves[move] = scorer(tablebase, board)
board.pop()
return moves


Expand All @@ -1380,7 +1384,7 @@ def score_gaviota_moves(board: chess.Board,
"""Score all the moves using gaviota egtbs."""
moves = {}
for move in board.legal_moves:
board_copy = board.copy()
board_copy.push(move)
moves[move] = scorer(tablebase, board_copy)
board.push(move)
moves[move] = scorer(tablebase, board)
board.pop()
return moves
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