Author: Robert Hyatt
Date: 20:21:37 08/11/04
Go up one level in this thread
On August 11, 2004 at 05:48:14, Gerd Isenberg wrote: ><snip> >>What I said was this: Hsu and I had a "discussion" about SEE vs MVV/LVA in >>rec.games.chess.computer. I claimed that SEE was better, he claimed MVV/LVA was >>just as good. >> > >Fine that this discussions are still available via google group search! >Very interesting reading. > >http://groups.google.de/groups?hl=de&lr=&ie=UTF-8&threadm=jwes.809762643%40BIX.com&rnum=22&prev=/groups%3Fq%3D%2522Feng-Hsiung%2BHsu%2522%26hl%3Dde%26lr%3D%26ie%3DUTF-8%26start%3D20%26sa%3DN > That is one of several, but not the one I was thinking of. IE I actually ran MVV/LVA vs SEE, and posted the results, with time, tree search size, etc for each... I didn't see any real data in the link you gave, although it does point out that "way back when" you could find lots of interesting things going on in r.g.c.c before it got overrun with idiots. > >>I first modified Crafty's q-search and normal search so that it used MVV/LVA to >>order captures (there was a version or two of this released so that others could >>run the tests as well). This version could _not_ prune captures as MVV/LVA >>doesn't give enough information to decide whether a capture loses or wins... IE >>if the largest piece hanging is a rook, and the smallest attacker is a queen, >>MVV/LVA tries QXR first, whether the rook is defended or not. >> >>I then modified the normal crafty to use SEE but without excluding losing >>captures, since MVV/LVA q-search had to try all captures for safety. >> >>I compared the two and found that SEE produced 10% smaller trees (this was on a >>fast machine for significant searches) but was 10% slower, meaning there was no >>advantage for either. >> >>Then I turned my original quisecence search pruning back on, something that >>works for SEE but not MVV/LVA and the tree size dropped by 50% over a test set >>of positions. This was based solely on the idea of (a) no SEE losing captures >>(no reference to alpha/beta or the infamous "delta pruning" I now use); (b) >>after 4 plies of q-search, no "exchanges" (even trades) either. That was what >>early Crafty did, copied from a simple CB q-search that I used after the normal >>CB q-search gave up on checks and threats and went to a simple capture-only >>search near the end of the variations. >> >>My current "delta pruning" approach is even more effective in eliminating >>q-search nodes. It would be easy to turn it off to compare tree sizes of >>course.
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