Stockfish 在完美功能上给出了矛盾的结果

Question

我正在开发一个 Unity 国际象棋程序，我正在使用 stockfish 通过比较 perft 函数结果来调试我的移动生成算法。

在这个深度为 2 的位置 (8/2p5/3p4/1P5r/1K5k/5p2/4P1P1/1R6 b - - 0 1) 上，Stockfish 给出了这个结果：

f3f2: 20
d6d5: 22
c7c6: 23
c7c5: 7
f3e2: 18
f3g2: 18
h5b5: 5
h5c5: 20
h5d5: 22
h5e5: 22
h5f5: 22
h5g5: 22
h5h6: 22
h5h7: 22
h5h8: 22
h4g3: 20
h4g5: 22
h4g4: 21

Nodes searched: 350

然后，如果我尝试通过将 fen 字符串更改为此 (8/8/3p4/1Pp4r/1K5k/5p2/4P1P1/1R6 w - - 0 1) 并将深度更改为 1 来应用移动 c7c5，Stockfish 仅提供 6 个输出：

b4a3: 1
b4b3: 1
b4c3: 1
b4a4: 1
b4c4: 1
b4a5: 1

Nodes searched: 6

所以它给出的输出是 6 而不是 7，正如它在深度 2 中所说的那样（c7c5: 7 意味着在移动 c7c5 之后有 7 种可能的对手反应）。为什么会这样？

position fen 8/2p5/3p4/1P5r/1K5k/5p2/4P1P1/1R6 b - - 0 1
d

 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 8
 +---+---+---+---+---+---+---+---+
 |   |   | p |   |   |   |   |   | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   | p |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   | P |   |   |   |   |   | r | 5
 +---+---+---+---+---+---+---+---+
 |   | K |   |   |   |   |   | k | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   | p |   |   | 3
 +---+---+---+---+---+---+---+---+
 |   |   |   |   | P |   | P |   | 2
 +---+---+---+---+---+---+---+---+
 |   | R |   |   |   |   |   |   | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: 8/2p5/3p4/1P5r/1K5k/5p2/4P1P1/1R6 b - - 0 1
Key: EF2C6A67E054E287
Checkers:
go perft 2
f3f2: 20
d6d5: 22
c7c6: 23
c7c5: 7
f3e2: 18
f3g2: 18
h5b5: 5
h5c5: 20
h5d5: 22
h5e5: 22
h5f5: 22
h5g5: 22
h5h6: 22
h5h7: 22
h5h8: 22
h4g3: 20
h4g5: 22
h4g4: 21

Nodes searched: 350

position fen 8/8/3p4/1Pp4r/1K5k/5p2/4P1P1/1R6 w - - 0 1
d

 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 8
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   | p |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   | P | p |   |   |   |   | r | 5
 +---+---+---+---+---+---+---+---+
 |   | K |   |   |   |   |   | k | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   | p |   |   | 3
 +---+---+---+---+---+---+---+---+
 |   |   |   |   | P |   | P |   | 2
 +---+---+---+---+---+---+---+---+
 |   | R |   |   |   |   |   |   | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: 8/8/3p4/1Pp4r/1K5k/5p2/4P1P1/1R6 w - - 0 1
Key: 17EBC3EFE240B12C
Checkers: c5
go perft 1
b4a3: 1
b4b3: 1
b4c3: 1
b4a4: 1
b4c4: 1
b4a5: 1

Nodes searched: 6

这是完整的命令

Answer 1

您使用的 FEN 有误。走c7c5后的FEN串是8/8/3p4/1Pp4r/1K5k/5p2/4P1P1/1R6 w - c6 0 2。你忘记了过路人广场。

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