Author: leonid
Date: 14:36:36 07/11/01
Go up one level in this thread
On July 11, 2001 at 15:20:17, Heiner Marxen wrote: >On July 11, 2001 at 14:33:12, Christoph Fieberg wrote: > >>On July 11, 2001 at 12:22:15, Heiner Marxen wrote: >> >>>On July 11, 2001 at 11:45:17, Christoph Fieberg wrote: >>> >>>>I composed the following position: >>>>[D]r2qk2r/8/8/qqqqqqqq/QQQQQQQQ/8/8/R2QK2R b KQkq - 0 80 >>>> >>>>Who can construct a game to reach it? >>>> >>>>In my first attempt I needed 161 moves (last move was 81.Ke1). >> >>161 moves was meant as half-moves! (as you could see from the notion 81.Ke1) >>Sorry, that I did not express excatly. > >I see! Sorry, could have guessed that myself. >To avoid this sort of confusion, in the context of computer chess half-moves >are often called "plies". > >>> >>>If the white K has moved, its castling rights KQ should be removed! >>> >> >>In my game both kings had moved! Therefore no castling possible any more. > >Aha. In that case the same mate in 8 does follow, but the solution time >of Chest reduces from 330.54 secs to 296.10 secs. I didn't expect the >difference to be that large... Chest still can surprise its author :-) Hi! I found this "strange" position to be very much like my "normal" one. When you indicated that it contain mate in 8, I thought that, probably, it is more that coincidence. LLchess mate solver. 600Mhz. No hash. Castling regarded as existing. First mate for white side found for 8 moves deep in 35 seconds. Obviosly mate for black side in 8 moves also existe and was found. Cheers, Leonid. >>>>Who needs less moves? >>> >>>IIRC, Popeye can construct proof games. But more than 300 plies? >> >>As explained only 161 plies are necessary! Can Popeye cope with it? > >I have no idea, since I did not really use that feature. >I have studied its source code for a similar job, i.e. help mates, >which uses basically the same technique. The program calculates a good >minimum distance between source and destination position and uses this >to prune early. > >Whether this method is good enough for this problem... I just don't know. >You could try it yourself: Popeye is sort of free (GNU copyleft IIRC). > >Regards, >Heiner > > >>Regards, >>Christoph >> >> >>>I cannot imagine any program to proove the shortest proof game for such >>>a position... but then, what do I know? >>> >>>>Best regards, >>>>Christoph >>> >>>Regards, >>>Heiner
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