Author: Heiner Marxen
Date: 12:20:17 07/11/01
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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 :-) >>>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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