Author: Robert Hyatt
Date: 11:59:14 12/21/99
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On December 21, 1999 at 10:26:14, Nicolas Carrasco wrote: >You conviced me to put SEE before MVV/LVA. I will make stats and I someone is >interested I will publicate them. > I did this a couple of years ago. SEE is over 10% more efficient in ordering captures. IE using SEE your tree will generally decrease in size by 10%. But once you have SEE, you can use it to weed out hopeless captures in the q-search (ie qxp pxq) and _that_ will cut the tree size by 50%. Or make you twice as fast, depending on how you look at it... The complete details were reported in r.g.c.c several years ago in a long discussion with Hsu about this... >On December 21, 1999 at 09:56:31, Robert Hyatt wrote: > >>On December 21, 1999 at 06:45:01, Daniel Clausen wrote: >> >>>Hi >>> >>>On December 21, 1999 at 00:36:03, Robert Hyatt wrote: >>> >>>>On December 20, 1999 at 13:02:38, Nicolas Carrasco wrote: >>>> >>>>>Do u know any documentation of MVV and LVA? >>>> >>>>This approach (MVV/LVA or Most Valuable Victim, Least Valuable Attacker) >>>>was designed for hardware move generators, as this is easy to do with some >>>>parallel hardware for each square. It works OK for normal chess programs, >>>>although SEE is generally better. >>>> >>>>It just means (a) find the most valuable piece that is attacked by the >>>>moving side, and then (b) capture it by the least valuable piece that is >>>>attacking it. >>>> >>>>Very simple to implement. >>> >>>This is what I'm also doing in my engine now. I noticed though that in >>>my case it's better to try the loosing capture also before the quiet >>>moves. I'm not sure whether this has to do with the relatively bad >>>quality for the MVV/LVA-value (compared to the SEE-value) or caused >>>by yet another silly mistake somewhere in my engine. >>> >>>Kind regards, >>> -sargon >> >> >>This is only true with MVV/LVA. Because it doesn't recognize 'losing' captures >>very well. QxR is not losing, if the queen has a bishop behind it, backing it >>up, and the rook is defended by a rook. So that QxR, RxQ, BxR is played. That >>wins a pawn. SEE would correctly recognize that this wins material and try >>it before moves like RxR which might (by MVV/LVA) either win a rook or be an >>even exchange. >> >>Once you add SEE, you can put off losing captures to the very end.
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