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Subject: Re: How much rating do program lose from null move pruning at fixed depth?

Author: Robert Hyatt

Date: 07:36:31 05/05/01

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On May 05, 2001 at 08:25:56, Uri Blass wrote:

>There is a possibility to set selectivity of Deep Fritz to 0 and it means that
>Fritz avoid null move pruning.
>
>The interesting question is how many effective plies are lost from null move
>pruning.
>
>Some results suggest that not very much
>
>Tiger14(depth3)-Deep Fritz(selectivity=0,depth 3)35-15(6 draws)
>Tiger14(depth4)-Deep Fritz(selectivity=0,depth 4) 31-19(8 draws)
>Tiger14(depth 8)-Deep Fritz(selectivity=0,depth 8) 20-23(12 draws) is going to
>be finished in an hour.
>
>The results without null pruning were not significantly better and at depth 3 it
>is not clear if selectivity=0 is productive because tiger could win only
>34.5-15.5 against selectivity=2.
>

Null-move gains at least 2 plies.  But it loses some as well, as a 3 ply
search with null move is not as good as a 3 ply search without...



>Fritz at depth d+1 at the default setting(selectivity=2) seems to be clearly
>better than Fritz at depth d(selectivity=0) at small depthes.
>
>I guess that at big depthes it changes but d=8 is not enough.
>
>Uri



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