Author: Bert van den Akker
Date: 14:46:37 09/13/99
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For position: 2r1r1k1/3p1p1p/p2Qp1p1/q1N2P2/Pn1B1P2/6P1/2P3bP/2KRR3 b - - With Hash: Depth Time used Total time used 1 0 0 2 0 0 3 2 2 4 4 6 5 13 19 6 9 28 7 25 53 8 115 168 Depth Time used Total time used 1 0 0 2 0 0 3 3 3 4 3 6 5 18 24 6 34 58 7 79 137 8 324 461 For this tactical position the gain is almost 1 ply because with hash a 8 ply search is done in 168 seconds and without hash 7 ply search ply is done in 137 seconds. The speed gain is (461/168)*100 =274% Positional position: LCT 2 Test position 11 bn6/1q4n1/1p1p1kp1/2pPp1pp/1PP1P1P1/3N1P1P/4B1K1/2Q2N2 w - - 0 1 id "POS-11 With Hash Depth Time used Total time used 1 0 0 2 0 0 3 0 0 4 1 1 5 4 5 6 4 9 7 6 15 8 19 34 9 71 110 10 288 398 statistics for ply 10: PV: h3-h4 g5xh4 f3-f4 h5xg4 f4xe5+ d6xe5 Pf1-h2 h4-h3+ Kg2-g3 Pg7-h5+ Kg3-h4 Kf6-g7 Le2xg4 Hash found/cutoff (6702436/308401) Null move done/cutoff (101792/76889) time = 236; score= 61 Without Hash Depth Time used Total time used 1 0 0 2 0 0 3 0 0 4 2 2 5 2 4 6 5 9 7 11 20 8 49 69 9 149 218 10 1588 1806 PV for ply 10: h3-h4 g5xh4 f3-f4 h5xg4 f4xe5+ d6xe5 Pf1-h2 h4-h3+ Kg2-g3 Pg7-h5+ Kg3-h4 Kf6-g7 Le2xg4 time = 1393; score= 61 Null move done/cutoff (361427/247503) For this positional position the gain is more then 1 ply. The speed gain is (1806/398) * 100 = 454% Conclusions for this positions: For this position the gain is much more then 100% and I expect this will grow if you hash table size is large enough. If a position must be researched so as on ply 10 (positional position) where the correct move h3-h4 was found hash tables will speed up the search because the moves are well ordered by the hash table. I think hash tables are essential for move ordering. An other good thing to have is History tables for your move ordering. Bert van den Akker
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