Author: Stuart Cracraft
Date: 20:53:00 08/21/04
Go up one level in this thread
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... > Thanks -- that will save a lot of time. I'll try to get this done in the next few days if possible. >Then minimax the result...
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