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Subject: an interesting bug in my move generator

Author: Uri Blass

Date: 14:07:31 12/31/01

My program had problems with WAC 250 so I decided to ask it to calculate the
perft function and found that it cannot calculate perft 4 correctly

The bug is that my program believed that double check from 2 rook directions is
impossible

Here is the position of WAC 250
[D]1b5k/7P/p1p2np1/2P2p2/PP3P2/4RQ1R/q2r3P/6K1 w - - 0 1

When I asked my program to calculate perft it failed in perft 4.

My program did not count correctly the number of moves after
1.a5 Ng8 hxg8Q+

it turns out that my program simply did not see that the rook does a check so it
believed that Qxg8 is a legal move.

My program also believes that double check from 2 diagnols is impossible and I
hope that at least it is not wrong with it.

Uri

• Re: an interesting bug in my move generator Heiner Marxen 18:06:49 12/31/01
  • Re: an interesting bug in my move generator Gian-Carlo Pascutto 10:03:47 01/01/02
    • Re: an interesting bug in my move generator Heiner Marxen 10:25:44 01/01/02
      • Re: an interesting bug in my move generator Uri Blass 11:36:48 01/01/02
      • Re: an interesting bug in my move generator David Rasmussen 11:30:46 01/01/02
        • Re: an interesting bug in my move generator Uri Blass 11:46:20 01/01/02
          • Re: an interesting bug in my move generator Heiner Marxen 13:02:12 01/01/02
            • Re: an interesting bug in my move generator Dann Corbit 14:48:46 01/01/02
              • Re: an interesting bug in my move generator Dann Corbit 16:30:50 01/01/02
  • Re: an interesting bug in my move generator Dan Andersson 06:37:47 01/01/02
• Re: an interesting bug in my move generator Georg v. Zimmermann 14:25:25 12/31/01

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