Author: Christophe Theron
Date: 20:05:23 01/12/01
Go up one level in this thread
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.
It is true that you need to measure the number of nodes to reach a given ply
depth on a number of typical positions before you can say which program is the
most selective.
However I can tell you in advance that you will (probably) discover that Chess
Tiger and Gambit Tiger are extremely selective. And the next versions will be
even more selective.
Christophe
>On January 12, 2001 at 03:20:26, David Rasmussen wrote:
>
>>My program Chezzz, and most of the programs I've been learning from and looking
>>at, has only little or moderate selectivity. Maybe I will keep it that way in
>>Chezzz, but what are the possibilities?
>>
>>As far as I know, there are two general kinds of selectivity as currently used
>>in "normal" alpha-beta based chess programs.
>>
>>1. Extensions
>>2. Forward pruning
>>
>>I would like to know what hints and tricks you guys have about extensions,
>>unusual extensions, how to limit extensions, when not to extend etc.
>>
>>But most of all, I would like to know about successful (I know this is somewhat
>>subjective) forward pruning techniques, that are actually used in programs.
>>
>>I compared my programs performance on the position below, with what Christophe
>>Theron posted from GT. At depth 10 the nodes searched by each programs are appx.
>>
>>GT : 1.290.000
>>Crafty : 13.500.000
>>Chezzz : 12.500.000
>>
>>So Crafty and Chezzz is the same, and they are both very conservative in regard
>>to selectivity IMO. I know that this is a choice and that one way is not better
>>than the other, but I would still like to know how programs such as GT can get
>>such a low node count.
>>
>>Now I know that GT is highly optimized, and that it has probably taken a long
>>time get as "efficent" as GT. But I would still like to know as much as possible
>>or at least the basics about how to forward prune succesfully like this.
>>
>>[D]2r1k2r/5pp1/4p3/ppqpP3/4bQPP/1B6/PPP2R1R/2K5 b k - 0 1
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.