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

Author: Alessandro Damiani

Date: 03:38:23 09/12/99

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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



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