Author: Jeremiah Penery
Date: 19:47:53 05/05/99
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On May 05, 1999 at 20:42:59, Paul Richards wrote: >On May 05, 1999 at 19:29:47, Francis Monkman wrote: > >> >>On May 05, 1999 at 18:55:03, Paul Richards wrote: >> >>>Strange thing though, as is so often the case, once you supply >>>the correct move, it sees the continuations immediately at a much >>>shallower depth. So then why the hell doesn't it see it by 15 ply? >>>It really does seem as though correspondence analysis would find >>>these thing faster. In other words, at 15 ply it doesn't see f5 >>>as best, yet as soon as you supply f5, it sees it winning within >>>10 or 11 ply. It doesn't get confused by any drawing chances >>>either, it easily finds a clear win. >> >>Exactly!! I've been noticing this 'phenomenon' for years, had new >>examples in the last few days. Haven't we all? Is there a fault in the >>search/pruning algorithm(s)? > >There usually seems to be a drawing possibility somewhere in the >search that throws a monkey wrench into the works. Crafty 16.6 >does particularly badly with this position. You can give it several >moves of the solution and it still doesn't see past drawing >possibilities. I would love to see a technical explanation for >this sort of thing. These solutions are well within the search >horizon, but yet they don't get found. In any case if this sort >of thing could be addressed effectively the programs would be much >stronger. I've noticed that Crafty in particular has trouble with these types of things - it seems to very much like draws by repetition, even when other lines seem to be clearly winning. That it also scores draws after only 2 repetitions in the search tree [but it's done correctly as 3 reps. of moves actually made] gives it trouble sometimes, as well. Properly detecting draws (And when not to draw) cause the most trouble for Crafty, I think. Jeremiah
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