Author: Bas Hamstra
Date: 07:40:23 01/13/01
Go up one level in this thread
On January 13, 2001 at 02:14:55, David Rasmussen wrote: >On January 12, 2001 at 22:08:50, Bas Hamstra wrote: > >>I don't know if it useful to compare nodes this way. My first PV at depth=10 >>comes in the order of nodes of GT, but then it switches 4 times, to end at a4 at >>22M nodes. I might be that GT was lucky to not have those expensive PV switches. >> >>Bas. >> >> > >I know that it is a possibility, but it was the only example I had of a program >that might have searched the position in considerably less nodes. Nevertheless, >there ARE programs that are more selective than Chezzz and Crafty, and >Christophe has countless times stated that he considers high selectivity far >superior to more conservative brute-forcedness, when implemented correctly. > >So regardless of whether this position is representative ro not, I would still >like to know a little bit about how the more selective programs achieve their >selectiveness. I suspect a combination of search based pruning like nullmove and evaluation based pruning. If you can write a piece of eval to determine a position is tactically safe for a couple of plies... Take nullmove. An amazing lot of nodes are pruned based on the qsearch only. But a typical mini-qsearch like Crafty's is far from reliable and has quite a bit of work to do too. You could write an piece of eval, with all kind of threat detections that go far beyond what such a qsearch can do in probably less ticks. For example (just a quick thought) what about pruning a position where white has a good eval and the opponent can not even attack one higher valued piece in one move? Where nullmove qsearch pruned nodes sort of establish that a position is 1-ply tactically save this would nearly mean that the opponent can hardly be dangerous within 2 of HIS plies. That is the direction I would think. Ciao! Bas.
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.