Author: Scott Gasch
Date: 09:52:57 11/28/00
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
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