Author: Peter Kasinski
Date: 05:50:20 03/17/99
Go up one level in this thread
On March 17, 1999 at 04:31:02, Cristian Zaslo wrote: >On March 16, 1999 at 22:55:09, Robert Hyatt wrote: > >>On March 16, 1999 at 18:36:08, Peter Kasinski wrote: >> >>>On March 16, 1999 at 16:58:09, Robert Hyatt wrote: >>> >>>>On March 16, 1999 at 12:04:51, Dann Corbit wrote: >>>> >>>>>On March 16, 1999 at 02:50:20, Cristian Zaslo wrote: >>>>> >>>>>>Hi everybody ! >>>>>>Will anyone be so kind and briefly explain me what sort of >>>>>>advantages would (not) have a chess programmer to implement >>>>>>a SEE in his code. >>>>>>Much obliged to you, >>>>>>Cristian >>>>>Er.... >>>>>What's a SEE? I've been programming 33 years and I have never heard of one. >>>> >>>> >>>>Stands for "Static Exchange Evaluator". It is a procedure that analyzes all >>>>captures on a single square and returns a value indicating who comes out >>>>ahead. >>>> >>> >>>>It can be used to order captures so that you try QxP where the pawn is free, >>>>before you try QxR where the R is defended. It can also be used to discard >>>>some captures in the q-search such as QxR where the R is defended and you are >>>>guaranteed to lose material. >>>> >>>>Used correctly it is possible to cut the size of the tree being searched by >>>>50% or more. >>> >>> >>>Bob, I looked at Swap() in Crafty where this is implemented. >>>Not using bitmaps I don't have a cheap way to determine what pieces attack a >>>given square. Would it still be profitable for me to compute these attacks in >>>order to use SEE? >>> >>>thank you, >>>PK >> >>There are far more non-bitboard programs than bitboard programs. And SEE >>works just fine. It will cost a little more probably, because there are >>loops that don't exist in bitmaps, but I had such a function in Cray Blitz. >> >>The idea is to take the target square, and first find out what pawns are >>attacking the square, then bishops, knights, rooks, queens and finally >>kings. Then the 'minimax' code at the bottom of my Swap() can be taken >>directly... > >So, am I right saying that SEE may be used to improve move ordering in the >Q-Search but it cannot be used as a single way to determine whether a leaf >node is or not a quiet one ? > >Thanks! But it leads to discarding some captures altogether. To me this means that SEE is used to: a) improve move ordering b) determine when you don't care if a leaf node is quiet or not because you discard the variation as futile. yes? PK
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