Author: Bas Hamstra
Date: 22:10:26 01/12/01
Go up one level in this thread
On January 12, 2001 at 23:05:23, Christophe Theron 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. > > > >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 No, no, don't do that! That's the way to promoting a pawn at move 216. Watching grass grow is far more interesting. Do you really want to score 55.1% at SSDF in stead on 54.93%? In stead of fireworks? Slightly worried, Bas. > > > > > >>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
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