Author: Sune Fischer
Date: 09:55:11 03/04/04
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On March 04, 2004 at 09:41:26, Tord Romstad wrote: >On March 03, 2004 at 06:04:29, Sune Fischer wrote: > >>On March 03, 2004 at 04:18:30, Paul Byrne wrote: >> >>>Granted, it is not a terribly useful position, as it came from a wild 8 (pawns >>>start on 4th rank) game on ICC between 2 patzers. And a very short search will >>>get you a score of +10 to +15 and better in white's favor. >>> >>>It is, however, surprisingly tough to see the mate, and makes an interesting >>>test position... >>> >>>r1b3n1/6k1/1n6/pP3qPQ/2PP2p1/1p4b1/4B3/R1BK2NR w - - 0 15 >>> >>>Guildenstern's normal search cannot see it here, while it's PN search gets it in >>>under 30 seconds on an athlon 2400+. The line the PN search produces is mate in >>>19, but is likely not optimal, as PN search is not terribly concerned with >>>winning in the least number of moves. >>> >>>So, what programs can see the win from here? >> >>Not mine, I get a +22 score though. > >Mine also doesn't find it. After 11 plies, the score is +29. The >problem might be that my search is "lazy" for the winning side in >positions where one side seems to have a winning advantage. I don't >extend checks, mate threats and other attacking moves as much as I >would do if the score were close to 0. The idea is that it is more >important to spend time looking for deep refutations of the apparent >win than looking for an even more crushing win. Ditto. It seems like a good principle, only it makes the engine look bad in test positions. >>How about this one from one of my recent games. >>I get a +13 score in a minute but no mate, I wonder if there is a mate >>within reach of any program? >> >>r4rk1/ppqb1Nbp/2n3p1/8/3PN1P1/1BP1Q2P/PP6/R4RK1 w - - 0 23 > >I don't find any. After 13 plies, the score is +16. With a mate you never know, it might be right around the corner!? :) -S. >Tord
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