Author: Peter Fendrich
Date: 13:30:42 12/14/04
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On December 14, 2004 at 14:55:41, E. Nielsen wrote: >Hi, > >We have got this little strange 'challenge' with our move-generator... ;-) > >There is this one perft-test from >http://homepages.caverock.net.nz/~peter/perft.htm >that fails from depth 3. > >r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - > >We get: >perft 1 >Total moves=48 [ok] >perft 2 >Total moves=2039 [ok] >perft 3 >Total moves=97898 [should be 97862 i.e 36 positions less] >perft 4 >Total moves=4087387 [should be 4085603 i.e 1784 positions less] > > >Is there anybody who has any idea on where such an error could originate? > > >Thanks in advance >Eyðun Nielsen One good method here that I lerarned from the program "Sharper" is to write another function (I call it perftm). It does exactly what perft does but for each move in the position. You will get something like: ------------------------------ >r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - perftm 3 (48 moves) = 0 Be2xa6 : 1907 1 Qf3xf6 : 2111 2 g2xh3 : 1970 3 d5xe6 : 2241 4 Ne5xg6 : 1997 5 Ne5xd7 : 2124 6 Ne5xf7 : 2080 7 Qf3xh3 : 2360 8 d5d6 : 1991 9 Bd2e3 : 2136 10 Bd2f4 : 2000 11 Be2d3 : 2050 12 Be2c4 : 2082 13 Ne5c6 : 2027 14 Ne5d3 : 1803 15 Ne5c4 : 1880 16 Bd2g5 : 2134 17 Be2b5 : 2057 18 Nc3b5 : 2138 19 Ne5g4 : 1878 20 Bd2c1 : 1963 21 Bd2h6 : 2019 22 Be2d1 : 1733 23 Be2f1 : 2060 24 Ke1g1 : 2059 25 Ke1c1 : 1887 26 Nc3a4 : 2203 27 g2g4 : 1843 28 g2g3 : 1882 29 b2b3 : 1964 30 a2a3 : 2186 31 a2a4 : 2149 32 Nc3d1 : 2040 33 Ra1d1 : 1885 34 Qf3d3 : 2005 35 Qf3e3 : 2174 36 Rh1g1 : 2013 37 Ra1b1 : 1969 38 Ra1c1 : 1968 39 Rh1f1 : 1929 40 Qf3g3 : 2214 41 Qf3f4 : 2132 42 Qf3g4 : 2169 43 Qf3f5 : 2396 44 Qf3h5 : 2267 45 Nc3b1 : 2038 46 Ke1d1 : 1894 47 Ke1f1 : 1855 Total: 97862 ---------------------------- Now compare the each moves figures with the right ones and select a move that differs. Make the move and do "perftm 2", compare again and so on. When you've reached "perftm 1" you see exactly what move is missing. You need a prgram to compare your numbers with. Download Sharper from http://www.albert.nu/programs/sharper/main.htm My "perftm 3" is called "divide 3" in Sharper. /Peter
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