Author: Stuart Cracraft
Date: 20:37:52 08/25/04
Go up one level in this thread
On August 23, 2004 at 23:53:02, Robert Hyatt wrote: >On August 23, 2004 at 10:14:54, Stuart Cracraft wrote: > >>On August 21, 2004 at 23:12:34, Robert Hyatt wrote: >> >>>On August 21, 2004 at 19:24:01, Stuart Cracraft wrote: >>> >>>>On August 21, 2004 at 17:52:58, Robert Hyatt wrote: >>>> >>>>>On August 21, 2004 at 17:37:15, Stuart Cracraft wrote: >>>>> >>>>>>On August 21, 2004 at 17:23:30, Robert Hyatt wrote: >>>>>> >>>>>>>On August 21, 2004 at 13:20:11, Stuart Cracraft wrote: >>>>>>> >>>>>>>>All, >>>>>>>> >>>>>>>>SEE increases my nominal iteration depth by 0.42 pawns >>>>>>>>given the same amount of time as a non-SEE search, all else >>>>>>>> >>>>>>>>SEE decreases my max quiescence depth reached (with a check handoff >>>>>>>>to main search) by a little under 8 ply for the same problem set. >>>>>>>> >>>>>>>>These are the 300 positions from Win-at-Chess run at 1 second per >>>>>>>>problem on an old, slow, notebook. I do not have comparative data >>>>>>>>due to the subjectivity involved of chess games and the "feel of SEE". >>>>>>>> >>>>>>>>Legend: >>>>>>>>Ave Iterative Depth/Average Max Search depth >>>>>>>>% solved >>>>>>>>Total solved / Total in test >>>>>>>>Total time taken (300 seconds allowed) >>>>>>>>Total Nodes searched >>>>>>>>Average positions searched per problem / >>>>>>>>Average time (rounded) per problem / >>>>>>>>Average nodes per second per problem >>>>>>>>0/0/Check Extensions from Quiescence back to Main Search/0/0 >>>>>>>> >>>>>>>>Without SEE >>>>>>>> >>>>>>>>**** 6.68/27.18 68% 204/300 269.05 54264704 180882/1/201692 0/0/3361112/0/0/0 >>>>>>>> >>>>>>>>With SEE >>>>>>>> >>>>>>>>**** 7.10/19.01 64% 193/300 267.44 46135172 153784/1/172505 0/0/1154026/0/0/0 >>>>>>>> >>>>>>>>Total problem solution rate drops 5.4% and nodes searched drops 14.98% >>>>>>>> >>>>>>>>(The SEE being used above was tried as (1) see < 0 then don't search >>>>>>>>a capture move in quiescence and (2) see < delta where delta is calculated >>>>>>>>with its margin off alpha as the maximum positional score so far in the >>>>>>>>search for the side on move. The above results are the combination of both and >>>>>>>>if only using the #2, assuming for example my SEE is not a great SEE, >>>>>>>>the result is only slightly changed.) >>>>>>>> >>>>>>>>My question is, why should SEE reduce the tactical result so drastically >>>>>>>>and is it safe to do so given the depth and nodes results are favorable? >>>>>>>> >>>>>>>>Thanks ahead, >>>>>>>> >>>>>>>>Stuart >>>>>>> >>>>>>> >>>>>>>SEE should _help_ in tactics, not hurt. If it is hurting, there is something >>>>>>>wrong somewhere... >>>>>> >>>>>>That's puzzling. I've tested it pretty thoroughly, manually, in a variety >>>>>>of positions and think it is working right. It knows nothing of any secondary >>>>>>effects, just the exchanging pieces. No x-rays, etc. >>>>>> >>>>>>Now I'm really nervous. >>>>> >>>>> >>>>>No x-rays is a serious shortcoming. IE two rooks attacking the same square in >>>>>battery. If you don't include the second rook I could see how SEE could cause >>>>>problems. I handle X-rays pretty easily and always did even back in CB days... >>>> >>>>Yes -- X-rays have to be added. Finding them isn't a problem. It's what to >>>>do with them after. I'll check around. >>> >>> >>>That part is simple. Produce a list of pieces directly attacking the target. >>>Each time you make a capture you _always_ use the smallest piece. And once you >>>use it, if it is not a knight or king, you look "behind" the piece you just used >>>to see if there is a piece that moves in the same direction. If so, add _that_ >>>piece to the list of attackers, and the next cycle you still use the smallest >>>piece from that list... >>> >>> >>>Repeat until one side runs out of capturng pieces... >>> >>>Then minimax the result... >> >>Bob, I understand why one doesn't do it for the knight, but why not the king? >>Example, a bishop and king on a diagonal. King captures pawn, some other >>recapture, then the knight before the king recaptures the recapturer. >> >>I thik you have to look "behind" everything except the knight for x-ray >>pieces, no? >> >>Stuart > >If the king captures on the target and is then captured, it doesn't matter >whether there was a piece behind it or not. That capture was illegal.. :) Yes -- I realized this after hitting the submit button on my "proud post". At least I was right on the pawn. Made my week.
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