def alphabetamax(self, position, alpha, beta, depthleft):
global nposition, isrunning, nalphacut, nbetacut
nposition += 1
if not isrunning:
raise StopSearchSystemExit
if depthleft == 0:
evaluator = evm.Evaluator(position.listpiece)
position.value = evaluator()
msg = position.outputmoves()
testfile.write(msg + "\n")
return
illegalmoves = []
for move in position.moves:
position.applymove(move)
if self.listpiece.is_white_king_in_check():
position.undomove(move)
illegalmoves.append(move)
continue
child = position.enemy_game_position_func(position.listpiece,
position)
try:
child.moves.sort(key=child.moveorderingkeybypriority,
reverse=True)
self.alphabetamin(child, alpha, beta, depthleft - 1)
except StopSearchSystemExit:
position.undomove(move)
raise StopSearchSystemExit
if child.value >= beta:
position.value = beta
msg = position.outputmoves()
testfile.write(msg + "---------- beta cut-off -----------" +
"\n")
position.undomove(move)
nbetacut += 1
return
if child.value > alpha:
alpha = child.value
position.children.append(child)
position.undomove(move)
for move in illegalmoves:
position.removemove(move)
if position.imincheckmate():
position.value = position.imincheckmatevalue
msg = position.outputmoves()
testfile.write(msg +
"********** CHECKMATE - GAME ENDED **********\n")
return
if position.isstalemate():
position.value = 0
msg = position.outputmoves()
testfile.write(msg + "********** DRAW - GAME ENDED **********\n")
return
position.value = alpha
return
def minimaxformin(self, position, depthleft):
global nposition
nposition += 1
if not isrunning:
raise StopSearchSystemExit
if depthleft == 0:
evaluator = evm.Evaluator(self.listpiece)
position.value = evaluator()
msg = position.outputmoves()
testfile.write(msg + "\n")
return
illegalmoves = []
for move in position.moves:
position.applymove(move)
if self.listpiece.is_black_king_in_check():
position.undomove(move)
illegalmoves.append(move)
continue
child = position.enemy_game_position_func(position.listpiece,
position)
try:
self.minimaxformax(child, depthleft - 1)
except StopSearchSystemExit:
position.undomove(move)
raise StopSearchSystemExit
position.children.append(child)
position.undomove(move)
for move in illegalmoves:
position.removemove(move)
if position.imincheckmate():
position.value = position.imincheckmatevalue
msg = position.outputmoves()
testfile.write(msg + "****** CHECKMATE - GAME ENDED ******\n")
return
if position.isstalemate():
position.value = 0
msg = position.outputmoves()
testfile.write(msg + "****** DRAW - GAME ENDED ******\n")
return
minchild = None
for child in position.children:
if minchild is None:
minchild = child
else:
if minchild.value > child.value:
minchild = child
position.value = minchild.value
return
def alphabetamin(self, position, alpha, beta, depthleft):
global nposition, isrunning, nalphacut, nbetacut, nmatch
nposition += 1
if not isrunning:
raise StopSearchSystemExit
record = position.getrecord()
if record is not None:
position.value = record.score
position.bestmove = record.bestmove
msg = position.outputmoves()
testfile.write(
msg + "________ Transposition table match ______________" +
"\n")
nmatch += 1
return
if depthleft == 0:
evaluator = evm.Evaluator(position.listpiece)
position.value = evaluator()
position.updatetranspositiontable(False, False, depthleft, None,
True)
msg = position.outputmoves()
testfile.write(msg + "\n")
return
illegalmoves = []
for move in position.moves:
position.applymove(move)
if self.listpiece.is_white_king_in_check():
position.undomove(move)
illegalmoves.append(move)
continue
child = position.enemy_game_position_func(position.listpiece,
transpositiontable,
position)
try:
child.moves.sort(key=child.moveorderingkeybypriority,
reverse=False)
self.alphabetamax(child, alpha, beta, depthleft - 1)
except StopSearchSystemExit:
position.undomove(move)
raise StopSearchSystemExit
if child.value <= alpha:
position.value = alpha
position.updatetranspositiontable(True, False, depthleft, None,
False)
msg = position.outputmoves()
testfile.write(msg + "---------- alpha cut-off -----------" +
"\n")
position.undomove(move)
nalphacut += 1
return
if child.value < beta:
beta = child.value
position.children.append(child)
position.undomove(move)
for move in illegalmoves:
position.removemove(move)
if position.imincheckmate():
position.value = position.imincheckmatevalue
position.updatetranspositiontable(False, False, depthleft, None,
False)
msg = position.outputmoves()
testfile.write(msg +
"********** CHECKMATE - GAME ENDED **********\n")
return
if position.isstalemate():
position.value = 0
position.updatetranspositiontable(False, False, depthleft, None,
False)
msg = position.outputmoves()
testfile.write(msg + "********** DRAW - GAME ENDED **********\n")
return
position.value = beta
position.updatetranspositiontable(False, False, depthleft, None, False)
return