Author: Dieter Buerssner
Date: 12:43:26 09/03/01
Go up one level in this thread
On September 02, 2001 at 18:22:26, Georg v. Zimmermann wrote: >The NullMove thing might be not too much of a problem. Shouldn't it happen very >very seldom ? I agree, that it should happen only rarely. Otherwise, we couldn't use null moves efficiently. But it can (an will) change results. And adjusting the window bounds from the hash complicates this again a bit. That was actually all, I wanted to point out. Some numbers from 22 postions of WAC searched for 2 million nodes. These were run with R=2, disabling any double null move tricks, and also disabling null move cutoffs. Just "probe" the null move and remember, if you would have gotten a cutoff. Then compare to the result of a normal search. Remember the cases, when the null move cutoff would have been wrong. Because I normally use fail soft, some more stringent comparision would ideally be needed. But I was too lazy for that now. I just looked, if both scores were >= beta. Also other pruning techniques should be taken into account, and how they interfere with null move. Still, the numbers may get a small idea. You will see a comparable low nomber of wrong null move fail highs, but still they can have a significant result. For examply WAC 141 (test.ci 7 down there) is usually found at ply 8 with null move, without null move it is found at ply 6 with my program. The 22 positions: 8/7p/5k2/5p2/p1p2P2/Pr1pPK2/1P1R3P/8 b - - bm Rxb2; id "test.ci 1"; 2kr3r/pp1q1ppp/5n2/1Nb5/2Pp1B2/7Q/P4PPP/1R3RK1 w - - bm Nxa7+; id "test.ci 2"; 8/p3k1p1/4r3/2ppNpp1/PP1P4/2P3KP/5P2/8 b - - bm Rxe5; id "test.ci 3"; r4rk1/1p2ppbp/p2pbnp1/q7/3BPPP1/2N2B2/PPP4P/R2Q1RK1 b - - bm Bxg4; id "test.ci 4"; 8/k1b5/P4p2/1Pp2p1p/K1P2P1P/8/3B4/8 w - - bm b6+ Be3; id "test.ci 5"; r2r2k1/pb3ppp/1p1bp3/7q/3n2nP/PP1B2P1/1B1N1P2/RQ2NRK1 b - - bm Qxh4; id "test.ci 6"; 4r1k1/p1qr1p2/2pb1Bp1/1p5p/3P1n1R/1B3P2/PP3PK1/2Q4R w - - bm Qxf4; id "test.ci 7"; r1bq4/1p4kp/3p1n2/p4pB1/2pQ4/8/1P4PP/4RRK1 w - - bm Re8; id "test.ci 8"; 5rk1/p4ppp/2p1b3/3Nq3/4P1n1/1p1B2QP/1PPr2P1/1K2R2R w - - bm Ne7+; id "test.ci 9"; 5rk1/2p4p/2p4r/3P4/4p1b1/1Q2NqPp/PP3P1K/R4R2 b - - bm Qg2+; id "test.ci 10"; rr4k1/p1pq2pp/Q1n1pn2/2bpp3/4P3/2PP1NN1/PP3PPP/R1B1K2R b KQ - bm Nb4; id "test.ci 11"; r1br2k1/pp2nppp/2n5/1B1q4/Q7/4BN2/PP3PPP/2R2RK1 w - - bm Bxc6 Rfd1; id "test.ci 12"; 2rqrn1k/pb4pp/1p2pp2/n2P4/2P3N1/P2B2Q1/1B3PPP/2R1R1K1 w - - bm Bxf6; id "test.ci 13"; 2b5/1r6/2kBp1p1/p2pP1P1/2pP4/1pP3K1/1R3P2/8 b - - bm Rb4; id "test.ci 14"; 5r2/1p1RRrk1/4Qq1p/1PP3p1/8/4B3/1b3P1P/6K1 w - - bm Qxf7+ Rxf7+; id "test.ci 15"; r5k1/pQp2qpp/8/4pbN1/3P4/6P1/PPr4P/1K1R3R b - - bm Rc1+; id "test.ci 16"; 2rq1rk1/pp3ppp/2n2b2/4NR2/3P4/PB5Q/1P4PP/3R2K1 w - - bm Qxh7+; id "test.ci 17"; 2r1k2r/2pn1pp1/1p3n1p/p3PP2/4q2B/P1P5/2Q1N1PP/R4RK1 w k - bm exf6; id "test.ci 18"; 2kr2nr/pp1n1ppp/2p1p3/q7/1b1P1B2/P1N2Q1P/1PP1BPP1/R3K2R w KQ - bm axb4; id "test.ci 19"; 2r1r1k1/pp1q1ppp/3p1b2/3P4/3Q4/5N2/PP2RPPP/4R1K1 w - - bm Qg4; id "test.ci 20"; 3q1rk1/4bp1p/1n2P2Q/3p1p2/6r1/Pp2R2N/1B4PP/7K w - - bm Ng5; id "test.ci 21"; 1nbq1r1k/3rbp1p/p1p1pp1Q/1p6/P1pPN3/5NP1/1P2PPBP/R4RK1 w - - bm Nfg5; id "test.ci 22"; And the corresponding statistics for null moves: null move: tried 199461, fail highs 130646, wrong 102 null move: tried 137714, fail highs 79226, wrong 4 null move: tried 82124, fail highs 69131, wrong 1 null move: tried 95967, fail highs 54452, wrong 0 null move: tried 273495, fail highs 189388, wrong 245 null move: tried 105239, fail highs 103096, wrong 4 null move: tried 155019, fail highs 101862, wrong 35 null move: tried 140807, fail highs 94361, wrong 4 null move: tried 163565, fail highs 103156, wrong 0 null move: tried 177757, fail highs 116430, wrong 42 null move: tried 112171, fail highs 61919, wrong 5 null move: tried 89585, fail highs 50509, wrong 0 null move: tried 103539, fail highs 63705, wrong 8 null move: tried 296831, fail highs 191852, wrong 326 null move: tried 196593, fail highs 136806, wrong 21 null move: tried 135310, fail highs 117776, wrong 11 null move: tried 129382, fail highs 120070, wrong 8 null move: tried 168999, fail highs 91865, wrong 10 null move: tried 134935, fail highs 86521, wrong 2 null move: tried 228132, fail highs 154049, wrong 18 null move: tried 74631, fail highs 65437, wrong 0 null move: tried 94449, fail highs 84651, wrong 0 Regards, Dieter
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