Author: Robert Hyatt
Date: 10:34:30 11/28/00
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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: Just a note. 2<<depth is not a good idea. what happens if you search to 32 plies? This is more than possible with today's hardware. Unless you are using a 64 bit integer. > >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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