Author: Tony Werten
Date: 13:42:13 08/01/03
Go up one level in this thread
On August 01, 2003 at 11:15:53, Angrim wrote: >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. Didn't think about that. So fail high by search are not exact. Tony > >Angrim
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