Author: Robert Hyatt
Date: 12:38:00 06/29/98
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On June 29, 1998 at 15:03:34, Peter Kasinski wrote: >Could someone please explain - what does "null move R=2" mean? >I realize this is a naive question. I actually added (what I thought was) a >null-move logic to my program and now I wonder. >In my code I first try a NULL move at all levels of the tree provided that last >move was not NULL and that a (basic) zugzwang-detection test is passed. > >Thank you. > >PK. R=2 is simple. In a normal search, you make a move, and then call search recursively as in value=-Search(-beta,-alpha,depth-1,etc.); After a null-move, you call search: value=-Search(-beta,-alpha,depth-1-R,etc); which means that you search two plies less deeply below the null than you normally would. That's where the big savings come from, that R=2. R=1 is more conservative. R=3 is more speculative...
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