Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Forward pruning and PVS, was Re: Interesting mate test for hashing,

Author: Alessandro Damiani

Date: 13:58:52 09/12/99

Go up one level in this thread


On September 12, 1999 at 10:17:42, Robert Hyatt wrote:

>On September 12, 1999 at 06:38:23, Alessandro Damiani wrote:
>
>>On September 11, 1999 at 22:25:24, Robert Hyatt wrote:
>>
>>>On September 11, 1999 at 17:48:55, Alessandro Damiani wrote:
>>>
>>>>On September 11, 1999 at 15:59:19, Ed Schröder wrote:
>>>>
>>>>>On September 11, 1999 at 15:36:18, Robert Hyatt wrote:
>>>>>
>>>>>>OK... then we are 'in sync' here it seems..
>>>>>>
>>>>>>As far as PVS, the main advantage is that since almost everything is searched
>>>>>>with a null-window, it saves nodes, _IF_ you do well at move ordering (I have
>>>>>>no doubt that you do well so PVS might be a win for you too)...
>>>>>>
>>>>>>It reduced my trees by 10% and loses nothing at all...  unless you screw
>>>>>>up move ordering, then it can make the tree bigger as you first search with
>>>>>>a null window, then you have to re-search with the normal window...
>>>>>
>>>>>Thus, PVS is aspiration search with a null-window? Is that all there is?
>>>>>
>>>>>Ed
>>>>
>>>>I think there is problem with the combination null-window and forward pruning:
>>>>forward pruning is not perfect. So there are more wrong cut-offs with PVS than
>>>>without. This could affect positional play.
>>>>
>>>>Alessandro
>>>
>>>
>>>I don't do forward-pruning at all. Other than the sort of similar idea that
>>>comes out of null-move search with R=2...
>>
>>But null-move is not perfect, too. So there are wrong cut-offs, mainly after
>>quiet moves.
>>
>>Alessandro
>
>
>I would _never_ argue with that.  :)
>
>It _definitely_ produces problems in the right kinds of positions. It sort of
>reminds me of banging your head against a brick wall for several minutes.  The
>only reason you would do that is because it feels _so good_ when you stop.  Null
>move is sort of like that...
>
>:)

What I mean is that you use R=2 and not R=1. There is a difference in accuracy.

Alessandro



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.