Author: Inmann Werner
Date: 16:27:34 12/23/98
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On December 23, 1998 at 19:12:16, KarinsDad wrote: >Hi all, > >I understand the basic concepts of a null move search, however, what I do not >quite understand is when in a chess program would it be used. Would you use it >just after non-quiescent searches, specific cases of nq searches (e.g. checks or >piece takes), or in other areas of the tree? > >Do you use it just to find bad moves or is there a way to find good moves with >it as well? > >And when you use it, how extensively do you search with it? > >Thanks in advance, > >KarinsDad I use Null move only in the "normal" alpha-beta (not in q-search) I do it in each (nearly each) position before trying any other move. After doing the null move I call normal alpha beta, but with less depth. There again can occur Nullmoves, but never allow 2 in a row. When I get back my value, and it is >= beta I stop this tree and return beta without trying any move. This reduces the tree a lot. (But is not a really sure thing, but wrking fine.) Second, if the value is rather deep (nearly mate) I extend the search with one ply, cause there anywhere is a mate threat possible. Works also fine. Dont forget: Beware of Zugzwang!! Wish a happy Christmas Werner
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