Author: Angrim
Date: 08:15:53 08/01/03
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 use fail-soft, and it isn't magic. If searching a quies node and the first capture you look at is good enough to fail high, then it will return the value of that capture without checking if there was a second capture that would be even better. So the value returned would not be an exact value. Angrim
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.