Author: Bert van den Akker
Date: 15:03:44 09/13/99
For position: 2r1r1k1/3p1p1p/p2Qp1p1/q1N2P2/Pn1B1P2/6P1/2P3bP/2KRR3 b - - With Hash: Ply 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 Without Hash Ply 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 Ply 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 Ply 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 for ply>10 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 movesare well ordered by the hash table. I think hash tables are essential for move ordering. An other good thing to have for your move ordering is History tables. In addition the use of Recursive Null will speed up also the search with more then 300% Bert van den Akker
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