Author: Uri Blass
Date: 05:04:43 08/09/04
Go up one level in this thread
On August 09, 2004 at 07:39:21, David B Weller wrote: >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 No There are trillion of uninteresting positions when check force a single reply and the side that give the check obviously winning because it is easier to force single reply when you already have a big advantage. mate threat may be also a result of a big advantage. It make no sense to extend every case when there is a single reply or every mate threat. It also make no sense to extend every check and extending the right part is always better. Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.