Author: KarinsDad
Date: 16:53:41 04/03/00
Go up one level in this thread
On April 03, 2000 at 16:49:22, Dan Newman wrote: >On April 03, 2000 at 10:56:08, KarinsDad wrote: > >>On April 03, 2000 at 05:00:20, Jan Pernicka wrote: >> >>>On March 31, 2000 at 14:17:12, KarinsDad wrote: >>> >>>> >>>>Could someone please explain how they implement their SEE function, when they >>>>use it, and what they use it for? >>>> >>>>Or possibly a good web site that explains it. >>>> >>>>Any help is appreciated. >>> >>> Excuse me, could someone explain to me in several sentences what is >>> SEE function good for? Thanks >>> Jan >> >> >>Good luck. >> >>That is what my original post asks for and I did not receive any good answers. >> >>KarinsDad :) > >In Shrike I use the SEE everywhere to order the captures before I try them. >I don't use the SEE to do actual evaluation but do use it to prune losing >captures in the quiescence search and to delay trying losing captures in >the full width search. Currently I put losing captures at the tail end. > >Implemention. In my SEE I do some initial stuff to record the results of >the first capture which is fixed by the move in question. Then I create >a bunch of bitboards containing the remaining pieces that bear on the square >in question. Then I cycle through them "capturing" with less valuable pieces >first, more valuable later, alternating between sides. As I'm doing this I >knock out pieces that bear on the square but are blocked. I also determine >if pieces bearing on the square become unblocked and put them back in their >respective bitboards so that they will be found on a later pass. (The >machinery is fairly complicated and does a bit more than described above.) >All the while an array is being filled out with the current balance. After >all the attacking pieces of one side or the other are exhuasted and captured, >I quit making passes. At that point I "mini-max" the values in that array >to determine where one side or the other can simply stop and retain the best >advantage. The score at this point is the score returned by the SEE. > >-Dan. Thanks Dan. How do you min-max? For example, a knight is on the square and protected by a rook. Two rooks in a battery attack it. Rxn rxR Rxr wins a knight. However, after Rxn, the attacking side is winning a knight. After rxR, the defending side is winning a rook for a knight. After Rxr, the attacking side again is winning a knight. Since it flip flops, how do you know when to stop? Is it when your capture no longer wins for you (regardless of what your opponent's capture just won for him)? KarinsDad :)
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