Author: Don Dailey
Date: 15:36:21 12/08/98
Go up one level in this thread
On December 08, 1998 at 16:00:23, Bas Hamstra wrote: >Bob, I *try* to use PVS but get very strange results! > >Here is what I do: > >- At any node the first move is searched(a,b) >- The first move is PV[0][Depth] *if* legal, otherwise best capture >- Search rest (a, a+1) > >Now if a value > a is returned it is *at least* a+1 > >Research that same move with (a,b) a being *same* as above > > >Now I get *NO* value > a??????????? > >So *proven* value is at least a+1 >And proven value is not greater than a > >Something definitely wrong here. Can you point me to some pseudocode >for PVS? Looked at Crafty source, but too complex to quickly see through >all the extensions/null/futilities/razoring/delta's etc... > > >Regards, >Bas Hamstra. Hi Bas, You description is correct, you have a different bug. There is a slight enhancement involving the window you use on the re-search but your description is not buggy, and your problem is elsewhere. First of all, I assume you are checking for a beta cutoff after searching the very first move with a,b. You didn't mention this but I assume it is a given. I would turn off the hash tables as a start and see if the problem goes away. In fact, it might be useful to turn off all strange features to isolate the problem. You could be having problems based on hash tables, lazy evaluation, selectiviy of any kind, or even evaluation function inconsistancies. The first culprit to check however will be the hash tables, the source of many evils. - Don
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.