Author: Christophe Theron
Date: 13:04:04 10/11/03
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On October 11, 2003 at 14:12:41, Uri Blass wrote: >On October 11, 2003 at 14:05:35, Steve Maughan wrote: > >>Christophe, >> >>>1) I have written an extra engine core ("FUGU") which is extremely "tight". It >>>updates an internal representation of the board that is simpler than the one >>>of the classical Tiger engine, and it does not apply all the rules of chess >>>(some rules like en-passant, castling, underpromoting and 50-moves rule are >>>complex to handle and slow the engine down significantly). Doing without some >>>rules in the deepest part of the tree goes mostly unnoticed and help to speed >>>the engine up tremendously. >> >>Now that is an interesting idea. I have heard of top programs that ignore some >>rules for the whole of the search tree (e.g. Junior 5 ignored underpromotion) >>but I haven't heard of anyone ignoring some rules when near the tips of the tree >>(which is most of the search). >> >>Regards, >> >>Steve > >I guess that ignoring the rules is dependent on alpha and beta(otherwise it is >dangerous because the program may see mate based on the assumption that the >opponent cannot play an enpassant capture and only later consider the capture >and find that the mate was an illusion). > >I hope that at least when new tiger announce mate it does not prune enpassent >captures or underpromotions of the opponent. > >Uri This technique can be indeed extremely dangerous. The FUGU engine, by a strict definition, does not play chess!!! But it's not new. As you say, the previous versions of Junior were not playing chess but a slight variant of chess. However it was playing chess brilliantly. I must pay attention to some cases like the one you mention. In this case FUGU would not say it's a checkmate. It would just return a low score (alpha). So far I have never seen any problem because of it. Christophe
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