Author: Bruce Moreland
Date: 13:12:18 11/29/00
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On November 28, 2000 at 12:52:57, Scott Gasch wrote: >Hi, > >I posted a couple of messages about move ordering yesterday and wanted to share >some results from my (limited) testing. I ended up implementing the suggested >"apparently losing captures" (MVV/LVA) after all others order. In one test >position this resulted in a tree 200k nodes larger at 8 ply but in two others it >resulted in a marginally smaller (under 40k nodes) tree at 8 ply. I will do >more testing on this matter but it may be a moot point because I intend to write >a SEE pretty soon. > >I also did some experimenting with ordering captures that take the last moved >enemy piece. At low search depth this seems to make some difference but at >higher depth this heuristic actually grew the tree in all three test positions I >tried. > >I also did some playing with history weight and settled on hist[x][y] += (2 << >depth). My numbers (this is total nodes searched until ply x including plys >1..x-1) for d2d4 d7d5 e2e4 e7e5 are currently: > >1. 45 >2. 621 >3. 3725 >4. 14146 >5. 38694 >6. 183449 >7. 598020 >8. 1286875 > >I am doing null move (R=2/3 depending on remaining and normal futility pruning >with a slightly larger than safe window on frontier nodes and in qnodes. I've >read about extended futility pruning and razoring too. I'd be interested in >other ideas to cut down the tree search size... be they other move ordering >heuristics or other pruning methods that are reasonably safe. How do the nodes >searched in the position given compare to other engines? > >Thanks again, >Scott Ferret (not sure what version, but it's pretty new), running on a P6/200. 1: 00:00:00.010 72 [6] 2: 00:00:00.040 699 [12] 3: 00:00:00.100 2130 [13] 4: 00:00:00.251 8730 [15] 5: 00:00:00.491 21200 [18] 6: 00:00:01.352 71758 [19] 7: 00:00:03.986 233566 [22] 8: 00:00:24.676 1605573 [28] 9: 00:01:46.754 7359845 [28] Numbers in brackets are maximum depth reached. bruce
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