Author: Mike Byrne
Date: 17:58:34 11/04/03
Go up one level in this thread
On November 04, 2003 at 14:39:50, Dieter Buerssner wrote: >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 The earliest mention of this position http://www.chess-archive.com/ccc.php?art_id=32541 ""White would have a forced mate in 14 moves! Don't try to put this particular position on Fritz5 or any other program, as it would never suggest 33. Rxg7+! as the stongest move!"" GM Shirov 11/98 Chess Life Programs were solving this at the time of the quote - just not Fritz 5. My standard modfied crafty solves this in about 30M nodes in 24 seconds. My old modified crafty from 1998 needed 60M nodes and about 2m and 24 seconds on a dual 400 Mhz. Pocket Chess Genius (600 mhz)needs about 6 minutes
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