Author: David B Weller
Date: 04:39:21 08/09/04
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On August 08, 2004 at 04:35:54, Tord Romstad wrote: >On August 08, 2004 at 01:47:12, Stuart Cracraft wrote: > >>Now my new question is what features do you think would help in solving >>problems rapidly. Extensions? > >Yes. But be careful -- It is easy to introduce lots of extensions which makes >your engine very good at solving problems, but which greatly reduce the >playing strength in real games. You should always play some test matches >before you decide whether you want to keep some new extension in your >program. > >The most useful extensions for solving problems rapidly are: > >1. Checks. > >2. Single reply to checks. > >3. Mate threats. These can be detected statically, or by using the return >value of a null move search. Extend if the null move search returns >-MATE_VALUE+Ply+2. Question/Comment: *Some* experiments have indicated better results from <-MATE_VALUE+300 [ie, any mate score]. Doesnt this make sense? Because, after all, mated is mated [an absolute score]. Then again, I suppose the distance to mate IS somewhat indicative of the actuall threat ... comments... > >4. Attacking moves. If you evaluate all internal nodes (as I do), compare >the value of the king safety component of the evaluation function before >and after a move is made. If a move dramatically reduces the opponent's >king safety, you extend. > >In order to avoid search explosions, you may want to use fractional >extensions. I extend by a full ply only for checks. > Tord, does this mean you extend less for the mate threat extension and the 1reply to check? It seems backward to me IMHO [I say this intuitively, not because of experimental data] It seems there are trillions of worthless checks but far fewer 1reply and mate-threats ... yes/no/maybe ?? >Tord
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