Author: Robert Hyatt
Date: 10:30:19 03/24/03
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On March 24, 2003 at 12:47:06, Will Singleton wrote: >On March 24, 2003 at 11:26:56, Robert Hyatt wrote: > >>On March 24, 2003 at 02:07:31, Will Singleton wrote: >> >>>Position from Baron – Amateur bm Qxc2 >>>[D]2rr3k/pb3ppp/4p3/4P3/1n1B3R/1P4P1/P1q4P/1Q1RKB2 w - - 0 30 >>> >>>For some reason, Ruffian and Crafty have a very tough time with this one. I >>>wonder whether this could be due to some similarity between them. A problem in >>>repetition detection, perhaps? On my machine, amd 1.6ghz: >>> >> >> >>I doubt I have any repetition detection problem. However, for each of the >>programs can >>you give the score for the move _prior_ to finding the correct move? >> >>IE if a program says +.3 then it is _not_ going to want to find a repetition. >>If a different >>program says -.3, then it will go for the repetition as soon as it is found. >> > >The position seems to afford some repetition themes. My thought was that after >Bxa7, Qc3+ might be scored as leading to indeterminate positions due to long >sequences of moves driven by repetition chances (if handled incorrectly). Thus >Qc3+ wouldn't be seen as refuting Bxa7. > >That was my idea after first looking at the position. Then when I saw you had >changed the rep code, the idea seemed justified without further analysis. > >The difference between Crafty 19.2 and 19.3 in this position is rather dramatic. > It doesn't seem likely to be the result of the extension change you mentioned. >Have you found many other positions with such improvements? > >Will The extension change is pretty significant. I don't remember any specifics now but when I tested and compared, the new approach seemed to find many things a ply or two quicker than the older way, without badly hurting performance in normal positions.
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