Author: Uri Blass
Date: 04:24:11 04/18/05
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On April 18, 2005 at 05:57:41, Ross Boyd wrote: >>>>Which makes me think a low legal move count would be a better indicator of when >>>>to avoid null moving, rather than the usual "if (total_side_to_move_pieces < x)" >>>>condition. I think Movei generates legal moves and so is able to use this >>>>method. >>>> >>>>Food for thought, >>>> >>>>Ross >>> >>>Yes >>> >>>Movei is using that method but unfortunately it cannot solve it in a reasonable >>>time probably because of other tricks that I use that may help in games but not >>>at test suites. >>> >>>Latest Movei does not see the mate at depth 17 and the branching factor from >>>depth 14 is very bad. >>> >>>It needs >>>20490 nodes to finish depth 14. >>>234720 nodes to finish depth 15. >>>3524639 nodes to finish depth 16. >>>54218505 nodes to finish depth 17. >>> >>>Uri > >Hmmm... that's a lot of nodes... if I recall correctly you don't do hash table >cuts, so that might explain the low depth. TRACE doesn't solve it either, and >gets to ply 40 almost instantly with a draw score only. If I switch off null >move, then it takes about 12 seconds (P3-600) to find the mate. Not sure now >what depth was needed. > >Ross The problem for movei is certainly not null move pruning because null move pruning is not used when the number of moves of the side to move is small. part of the problem is check extensions and part of the problem is probably pruning based on evaluation together with other factors that I should improve. Note that pruning based on evaluation made movei weaker in test suites but stronger in games. Uri
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