Fix bogus mate scores in some positions
authorJoona Kiiski <joona.kiiski@gmail.com>
Fri, 22 Mar 2013 07:54:03 +0000 (08:54 +0100)
committerMarco Costalba <mcostalba@gmail.com>
Sat, 23 Mar 2013 20:28:51 +0000 (21:28 +0100)
commit09f1fdf52fe67b500f1a0159da9e53e9e3456679
tree68b105aaa44e33a5e9045ddb831ef9e19e4f922a
parentd39b22927e432adb9c06c718ce577f6647d5b07d
Fix bogus mate scores in some positions

Always before pruning the move, it's important to check that:

bestValue > VALUE_MATED_IN_MAX_PLY

See example position:

8/2p1p3/P1NpP3/3k4/1P1BN3/2P1P3/2Q5/6K1 w - - 0 1
http://support.stockfishchess.org/discussions/problems/268-wrong-declaring-a-forced-mate-in-3-moves

This problem was present in 2.3.1, then it was fixed by my patch.

After 24000 games at 15+0.05
ELO: 2.40 +-4.4 (95%) LOS: 95.7%
Total: 24000 W: 4774 L: 4608 D: 14618

bench: 4465997
src/search.cpp