Author: James Robertson
Date: 01:34:49 08/20/99
My program played a game in which this position arose: r3r1k1/3b1p1p/2p4q/p2p4/3P2p1/1PNPPpP1/P1RQ1P1P/5RK1 w - - It then played, after an 8 ply search, 1. e4?? which loses immediately to Qh3 and the loss of the queen after 1. e4?? Qh3 2. Qg5+ 3. Qf8 Qh6+ 4. Qxh6, an incredibly simple tactical sequence. I later ran my program on this position and it switched to the much much better move Kh1 after 6 plies. The only differece I can think of between the two searches would be the hash table? During the game it had entries from previous searches, and afterwards I ran it as a testsuite position with a clean table. I cannot fathom why else my program would miss such a thing in an actual game. Is there any reason why a hash table would do this? Is there some depth/draft thing I am messing up with my table? Is my null move causing problems? Any help anyone can provide is greatly appreciated. James P.S. Here are the two searches: a) during the game. Depth Score Time Nodes PV 1 216 0 35 Rfc1 2 200 0 250 e4 Qxd2 Rxd2 3 202 60 1263 Rfc1 Qh3 e4 4 203 170 9783 e4 Qg7 Qe3 Rab8 5 207 220 12885 e4 Qxd2 Rxd2 Be6 Rc1 6 202 330 20163 e4 Qxd2 Rxd2 Be6 Rc1 Rab8 Rdc2 7 199 550 40726 e4 Qxd2 Rxd2 Be6 Rc1 Rab8 Rdc2 Rb7 8 199 1050 89464 e4 Qxd2 Rxd2 Be6 Rc1 Rab8 Nb1 Rb6 Nc3 b) after the game with a fresh hash: Depth Score Time Nodes PV 1 216 0 32 Rfc1 2 200 0 255 e4 Qxd2 Rxd2 3 202 270 1457 Rfc1 Qh3 e4 4 203 380 10068 e4 Qg7 Qe3 Rab8 5 199 440 14046 e4 Qxd2 Rxd2 Be6 Rc1 Rab8 6> -160 660 38006 Ne2 fxe2 Qxe2 a4 Rb1 Qh3 e4 axb3 Rxb3 6> -159 770 46432 b4 axb4 Nxd5 cxd5 Qxb4 Qh3 6> 50 770 47608 h4 gxh3 Kh2 6> 176 820 51711 Kh1 Qh3 Rg1 f5 Rcc1 Rab8 6 176 820 51949 Kh1 Qh3 Rg1 f5 Rcc1 Rab8 7 178 1100 76625 Kh1 Qh3 Rg1 f5 Rcc1 Rab8 Rge1 8 184 2250 191340 Kh1 Qh3 Rg1 f5 Qd1 Rab8 Qf1 Qxf1 Rxf1 9 184 5110 452120 Kh1 Qh3 Rg1 f5 Qd1 Rab8 Qf1 Qxf1 Rxf1 10 176 9060 845582 Kh1 Qh3 Rg1 f5 Rcc1 Rab8 Na4 Rb4 Nc5 Be6
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