Author: scott farrell
Date: 05:03:29 01/15/03
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On January 15, 2003 at 06:12:23, David Rasmussen wrote: I went through this recently also. Robert said in crafty, he pretty much ignores it, and uses the drawscore as a fail high if it happens. I took a safe approach, return INVALID if you find any sort of draw during nullmove. I also try to stop nullmoves from occuring if it is close to any sort of draw or blocked position. Real moves are just as fast anyway. Scott >Since null moves are illegal in the real game, it is not obvious how it affects >or should affect repetitions and the fifty move rule. >What I do now in Chezzz is just pretty much ignore the relation between these >concepts and formulate them as if they were formulated in isolation. >What is the correct way to deal with these things? >For instance: > >1. What to do with the fifty moves rule counter when doing a null move? >2. When doing a null move, we obtain a new position, one that can never be > on the board immedeately after the currect position in a real game, but > it is treated as a "normal" position. What if a "repetition" is found of > two of these "imaginary" positions in the current line? We would return a > draw (that is what I do, since I treat these positions as all others, as do > most programs I've seen, Crafty for instance). > >I understand the need for draw detection and I understand the benefits of null >move pruning, but I think they affect eachother in an unclear way. What do >others do, and is there a way that is *correct*, and why? > >/David
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