Author: Steve Maughan
Date: 07:56:07 12/31/00
Go up one level in this thread
Bob, >>Surely at least when alpha is raised this is equivalent to finding a new best >>move and hence the PV needs to be cut off? > >I don't think so. I don't do this in Crafty, yet I raise alpha and lower beta >just as you do. All the hash entry says is "this position should have a higher >alpha bound (or lower beta bound)..." but it says nothing at all about a PV >since you still have to keep searching... As an example, suppose that initially Alpha = 1.00, Beta = 5.00 . From the hash we find a deeper search with a lower bound of 3.00. It is possible that had we not changed alpha and after the node has been searched the score for this node would be +2.00 and it could have formed part of the PV. However, if we raise alpha to 3.00 the search will fail low and therefore the node cannot be part of the PV. This doesn't seem right. Am I missing anything? I'll have a fiddle with my code and see if I come to any conclusions. Regards, Steve
This page took 0.01 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.