Author: Robert Hyatt
Date: 15:15:47 07/31/03
Go up one level in this thread
On July 31, 2003 at 14:23:34, Tony Werten wrote: >On July 30, 2003 at 17:18:12, Rick Bischoff wrote: > >>>> >>>>a. at depth 3- hash table is empty for this position. alpha = -INF, beta = +INF >>>>a. all requirements for null move are met >>>>a. makes null move: int e = -alphabeta(depth - 3, -beta, -beta +1); >>>> >>>>b. now we are at depth 0, alpha = -INF, beta = -INF + 1 >>>>b. we call quies(alpha, beta) >>>> >>>>c. e = static eval is, oh say, 1. >>>>c. e >= beta, return beta >>>> >>>>b. store this position in the hash table as -INF + 1, exact, depth = 0, return >>>>-INF + 1 >>> >>>This is _way_ wrong. How can it be "exact"??? It is impossible for the >>>search to return valid scores outside alpha/beta window as defined at the >>>root. If you are returning an "edge" then it must be an upper or lower >>>edge, not an exact score. >> >>Yes, I know it is wrong-- which is why I was asking the question to begin with >>:-) What I do know is store anything quies returns as exact-- but you are >>telling me I can't do that, right? (Forgive my ignorance!) > >You are correct (despite what the others say), but only if you use the failsoft >version of alphabeta. > >Tony I don't see how he can be correct even with failsoft. If you get a score outside alpha/beta it is _never_ an exact score, it will only be a bound.
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