Author: Russell Reagan
Date: 02:00:06 01/02/03
I'm trying to nail down this bug in my move generator. I'm calculating perft for positions and verifying them with other perft calculating engines. First I did perft with only kings on the board, and things seemed fine. Then I added queens, and things seemed fine. Then came the kings and rooks, and things seemed fine when castling wasn't involved, but then I tried the following position: [D]r3k2r/8/8/8/8/8/8/R3K2R w KQkq - 0 1 Things stopped being fine. Other engines I tried got perft(4)=314346, but mine gets perft(4)=314340, off by 6 nodes. Since there are *only* 26 legal moves in the above position I set out to try each one, calculate perft, and find the branch branch (or branches) containing the errors. The move Rb1 leads to a position that my engine incorrectly calculates perft 3. So I had an incorrect perft 4, and I found one branch that has an incorrect perft 3, so I'm on the right track (or so I thought). I tried each move from the position after Rb1, and to my suprise not one move turned up an incorrect perft 1 or perft 2, which is what I was expecting. It seems like this shouldn't happen. Am I missing something? Or is this yet another bug? Russell
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