Author: Dieter Buerssner
Date: 11:39:50 11/04/03
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On November 04, 2003 at 11:06:27, leonid wrote: >Try the next position that have good branching factor and, probably, will be >easy to solve by selective, or by brute force search. Hmmm. I used my chess engine (Yace), which in your terminoligy, you would probably call selective. It still should be reliable (never announce a mate in x, when there is no mate in x but perhaps only a mate in x+1/2/... Of course it might announce mate in x, when mate in x-1/2/... is possible). I did neither get a good branching factor, nor an easy solution .... > 1qkrr3/Rn2q3/PRPBqQ2/nqpbqB2/NQ2Nb2/1Q2Qq2/1Q2Qq2/1K2Qq2 w - - ... actually got no solution at all in 30 minutes on my P4 2.53 GHz with 100 MB hash and using about 50% of the CPU (another analysis, that I did not want to stop is running at the same time with more hash). Perhaps, it might be easy by selective search, when extending more aggressively (many checks in a row are possible). BTW. It took 17 seconds to finish the depth 1 search. I guess many engines will evene need longer (but did not try any). Branching factor from depth 1 to 2 was indeed good (17 s, then 21 s). ply 3: 1:02, 4: 14:20. Hardly one could consider it good ... I don't complain at all, but personally (and probably I am not the only one here), I find more "natural" chess positions for mate problems more interesting. Of course, it was my choice, to test your position anyway (I was curios). Especially, I would find those problems most interesting, where a mate comes rather surprisingly after a rather balanced score. Seeing several iterations in a row with rather high score from almost the beginning seems less interesting for normal playing engines. Sure, when we have 12 Qs on the board already, a rather high score may not mean much. You are probably aware, that the position cannot be reached in a chess games. My favorite mate problem (already discussed here several times) is: 6r1/2rp1kpp/2qQp3/p3Pp1P/1pP2P2/1P2KP2/P5R1/6R1 w - - Regards, Dieter
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