MinMax 函数在深度 = 3 时崩溃

Question

我正在通过使用卷积神经网络评估特定的棋盘状态来编写国际象棋 AI，然后我使用该评估来应用 min_max 算法来获得 AI 的移动。当我的算法的深度超过 2 时，我收到有关将元组与标量进行比较的错误。

def NN_evaluate(board):
    board3d = split_dims(board)
    board3d = np.expand_dims(board3d, 0)
    return model.predict(board3d)[0][0]


def minimax(board, depth, alpha, beta, maximizing_player):
    if depth == 0 or board.is_game_over(): 
        return NN_evaluate(board)
    moves = board.legal_moves
    
    if maximizing_player:
        max_eval = -np.Inf
        for move in moves:
            board.push(move)
            current_eval = minimax(board, depth-1, alpha, beta, False)
            board.pop()
            max_eval = max(max_eval, current_eval)
            best_move = move
            alpha = max(alpha, current_eval)
            if beta <= alpha:
                break
            return max_eval
    else: 
        min_eval = np.Inf
        for move in moves:
            board.push(move)
            current_eval = minimax(board, depth-1, alpha, beta, True)
            board.pop()
            min_eval = min(min_eval, current_eval)
            best_move = move
            beta = min(beta, current_eval) 
            if beta <= alpha:
                break 
        return min_eval
    
def get_ai_move(board, depth, maximizing_player):
    max_move = None
    max_eval = -np.inf  
    for move in board.legal_moves:
        board.push(move)
        current_eval = minimax(board, depth-1, -np.inf, np.inf, False)
        board.pop()
        if current_eval > max_eval:
            max_eval = current_eval
            max_move = move
    return max_move


board = chess.Board()

with chess.engine.SimpleEngine.popen_uci('C:\Users\coope\Downloads\Python\Machine Learning\Chess AI\stockfish_15_win_x64_avx2\stockfish_15_x64_avx2.exe') as engine:
    while True:
        move = get_ai_move(board, 3, True)
        board.push(move)
        print(f'\n{board}')
        if board.is_game_over():
            break

        move = engine.analyse(board, chess.engine.Limit(time=1), info=chess.engine.INFO_PV)['pv'][0]
        board.push(move)
        print(f'\n{board}')
        if board.is_game_over():
            break

错误如下

TypeError                                 Traceback (most recent call last)
~\AppData\Local\Temp/ipykernel_1108/561116885.py in <module>
      3 with chess.engine.SimpleEngine.popen_uci('C:\Users\coope\Downloads\Python\Machine Learning\Chess AI\stockfish_15_win_x64_avx2\stockfish_15_x64_avx2.exe') as engine:
      4     while True:
----> 5         move = get_ai_move(board, 3, True)
      6         board.push(move)
      7         print(f'\n{board}')

~\AppData\Local\Temp/ipykernel_1108/3382320008.py in get_ai_move(board, depth, maximizing_player)
     40     for move in board.legal_moves:
     41         board.push(move)
---> 42         current_eval = minimax(board, depth-1, -np.inf, np.inf, False)
     43         board.pop()
     44         if current_eval > max_eval:

~\AppData\Local\Temp/ipykernel_1108/3382320008.py in minimax(board, depth, alpha, beta, maximizing_player)
     28             current_eval = minimax(board, depth-1, alpha, beta, True)
     29             board.pop()
---> 30             min_eval = min(min_eval, current_eval)
     31             best_move = move
     32             beta = min(beta, current_eval)

TypeError: '>' not supported between instances of 'float' and 'NoneType'

这似乎是我的 min(min_eval, current_eval) 的问题，但我不确定如果 get_ai_move(board, 2, True) 不崩溃，如何解决它。

Answer 1

你的

    return max_eval

在for循环里面，应该在外面。像这样写存在不执行的情况，因此整个函数returns None（默认return value in python if you don't return 函数中的任何内容)

MinMax 函数在深度 = 3 时崩溃

MinMax function crashes on depth = 3

tuples

machine-learning

minmax