Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Delta Pruning (reply to Bob)

Author: Stuart Cracraft

Date: 21:09:16 08/10/04

Go up one level in this thread


Okay, so I just robbed from Peter (GNU) to try it with Paul (GA).

Relevant code is:

quiesce
   :
  while another capture
#ifdef DELTAPRUNE
#define MARGIN 200
    delta = MAX(alpha-MARGIN-baseval,0);
    if (see(bd,qml[mvi].to) < delta) {
      mvi++;
      continue;
    }
#endif
   proceed normally
   :

This uncovers the following improvement:

// without delta
//  2.02j 7.10/25.40 93% 28/30 25.89 6803985 226800/1/262783 0/0/310215/0/0/0

// with delta (GNU style)
//  2.02j 7.80/18.07 93% 28/30 25.01 5822842 194095/1/232811 0/0/113356/0/0/0

So searching 0.7 ply deeper in the main search and much less in the quiescence
with 14% fewer nodes.

Probably something better than this is possible.

It can also always use see>=0 restriction after "proceed normally" above
more cutoffs. I'll try the overnight run with a combination of nothing,
delta, and see>=0.

Stuart




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.