Author: blass uri
Date: 01:35:57 10/08/98
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On October 08, 1998 at 04:28:13, Kai Lübke wrote: >On October 08, 1998 at 02:03:56, blass uri wrote: > >> >>On October 07, 1998 at 23:33:53, James T. Walker wrote: >> >>>I gave Fritz 5.16 a position /p4K/P////k// W. I think that I have that figured >>>out right. Anyway, Fritz announces #14 after about 16 sec. But when you go >>>through the moves it announces #13 twice, #10 twice,#8 followed by #9 etc. It >>>jumps from #6 to #4 no matter what move I make in that position. After that it >>>counts on down to mate properly. It ends up with about a mate in 17. What >>>causes this phenom ? Crafty with the same position announces #17 on the first >>>move then while pondering it finds mate in 15. After that it counts down by one >>>to mate. That seems fairly normal. >>>Jim >> >>Fritz never knew to count >>It was designed to play chess and not to count the number of moves to mate >> >>I think that this is because of hash tables >>Maybe fritz found that some position leads to mate and remember it in the hash >>tables as mate without the number of moves >> >>After it go to the same position again in the search it evaluates it as >>checkmate without number of moves and this is the reason that it cannot count > >The "mate in 8, then on the next move mate in 9" stuff is something you often >see in Fritz engines (Hiarcs and Junior have the same problems sometimes). >Crafty has a special code that assures that a "mate in N" is never followed by >a "mate in N+k" where k>=0. >I'm just waiting for someone to find a position where Fritz will not be able to >mate because of this... :-) > >--- >Shep The main problem with fritz is that often the mate in N is only an illusion of fritz. It is a bad idea to use a special code for fritz telling it to look after mate in N only for mate in N-1 or less before solving this problem because the result may be: no mate found. Uri
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