Author: Dann Corbit
Date: 11:25:36 04/18/02
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On April 17, 2002 at 23:59:39, Ricardo Gibert wrote: >On April 17, 2002 at 15:43:23, Jesus de la Villa wrote: > >> >>Have someone defined the general rule(s) where null move >>is unable to find simple combinations?, and if so, which >>are those rules ? >> >>"Obviusly" is more expensive to check it than to not >>use Null Move. >> >>Thanks for asking >> >> >> >>PS. I hope you undertand my poor English :) > >Nullmove assumes that having the move is better than not. This assumption is not >correct for zugzwangs, so nullmove will have a problem with those positions >where zugzwang is relavant. It fails quite badly, so some care is needed in >avoiding this. Not using it in the endgame where zugzwang occurs with >significant frequency is one way. Another idea is "double nullmove". > >Pseudo-zugzwang, where having the move results in a delay in attaining a >favorable result, is fine for nullmove. In fact, it makes out like a bandit by >allowing a program to find a favorable result more easily than it would >otherwise. Unfortunately, these also only occur with significant frequency in >the ending where nullmove is typically turned off :-( Could you explain pseudo-zugzwang or show an algorithm snippet that demonstrates it? I have never heard of it before.
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