Author: Scott Gasch
Date: 14:17:47 12/18/00
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Hi, In the past couple of weeks I was working on my hash code. In the process I used this position a lot and found some interesting things. 1. If your hash replacement scheme is replace only if deeper you will be very slow on this position. I believe this is because the table (mine is 10 Mb) gets filled with deep nodes and cannot make use of shallow transpositions once it is. 2. If you replace always you will be very fast on this position but not others. The "right thing to do" in my opinion is to have a mix of both of these schemes. 3. You may have other bugs than simple replacement scheme bugs that are causing your slow performance. If I was you I would reread my hash code and make sure everything checks out. I don't know what your current replacement scheme is but you might try changing to always replace. See if it is not very fast when you do that. Once you have it working with always-replace, see if you can get it to work with a mixture replacement scheme... I found that this was a better solution in typical positions. Here's my output w/ a 5 sec search, FYI: set 8/k7/3p4/p2P1p2/P2P1P2/8/8/K7 w - - 0 0 st 5 go Think for 5.0..5.0 seconds. 1 78 0.0 4 a1b2 2 74 0.0 17 a1b2 a7b6 3 78 0.0 53 a1b2 a7b6 b2c3 4 78 0.0 125 a1b2 a7b6 b2c3 b6c7 5 82 0.0 258 a1b2 a7b6 b2c3 b6c7 c3c4 6 82 0.0 440 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 7 82 0.0 734 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 8 82 0.0 1115 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 9 82 0.0 1553 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c4 10 82 0.0 2237 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3e3 c7b6 11 82 0.1 2953 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c2 c7b6 c2d3 12 82 0.1 3812 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c3 c7b6 c3c4 b6c7 13 82 0.1 5046 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c2 c7b6 c2b3 b6c7 b3c4 14 80 0.1 7136 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c3 c7d7 c3c2 d7e7 c2d3 e7f6 15 80 0.1 8567 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c2 c7d7 c2b3 d7e7 b3c4 e7f6 c4d3 16 82 0.1 11067 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c3 c7b6 c3c4 b6a6 c4d3 a6b6 d3e3 b6c7 17 82 0.1 12702 a1b2 a7b6 b2c3 b6c7 c3c4 c7b6 c4d3 b6c7 d3c3 c7b6 c3c4 b6a6 c4d3 a6b6 d3c2 b6c7 c2d3 18 82 0.1 16091 a1b2 a7b6 b2c3 b6b7 c3c4 b7b6 [TT] 19 82 0.2 20453 a1b2 a7b8 b2c3 b8b7 [TT] 20 82 0.2 25133 a1b2 a7a8 b2c3 a8b7 [TT] 21 82 0.2 30920 a1b2 a7a8 b2c3 a8b7 [TT] 22 148 0.3 38575 a1b1!! 22 163 0.4 55291 a1b1 a7b7 b1c1 b7c7 c1d1 c7d7 d1c2 d7e7 c2b3 e7f6 b3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 b6c7 f4e4 c7d6 e4d4 23 186 0.4 61185 a1b1 a7b7 b1c1 b7c7 c1d1 c7d7 d1c2 d7e7 c2b3 e7f6 b3c4 f6g6 c4b5 g6h5 b5a5 h5g4 a5b6 g4f4 b6c7 f4e4 c7d6 e4d4 a4a5 24 236 0.5 73991 a1b1!! 24 274 0.7 83964 a1b1 a7b7 b1c1 b7a8 c1d2 a8b7 d2e3 b7b6 e3f3 b6c7 f3g3 c7d7 g3h4 d7e7 h4g5 e7f8 g5f5 f8f7 f5g5 f7g7 f4f5 g7g8 f5f6 g8f7 25 298 0.9 103622 a1b1 a7b8 b1c2 b8a8 c2d2 a8b7 d2e3 b7b6 e3f3 b6c7 f3g3 c7d7 g3h4 d7e7 h4g5 e7f7 g5f5 f7g7 f5g5 g7f7 f4f5 f7e7 [TT] 26 298 1.3 136239 a1b1 a7b7 b1c1 b7b8 c1c2 [TT] 27 244 1.5 175428 FL 27 82 1.6 182011 a1b1 a7b7 b1c2 b7b8 c2b3 b8c7 b3c4 c7b6 c4d3 b6c7 d3c3 c7b7 c3b2 b7a8 b2c1 a8b7 c1d2 b7c8 d2e3 c8d7 e3f3 d7e7 f3e2 e7f7 e2d3 f7g6 d3e3 28 143 1.8 203023 a1b1!! 28.5 82 5.0 522479 a1b1 a7b7 b1c2 b7b8 c2b3 b8c7 b3c4 c7b6 c4d3 b6c7 d3c3 c7b7 c3b2 b7a8 b2c1 a8b7 c1d2 b7c8 d2e3 c8d7 e3f3 d7e7 f3e2 e7f7 e2d3 f7g6 d3e3
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