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Subject: Re: A case when Movei earn 2 plies from verified null move pruning

Author: Uri Blass

Date: 16:16:59 11/22/02

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On November 22, 2002 at 18:57:06, Sune Fischer wrote:

>On November 22, 2002 at 18:09:28, Uri Blass wrote:
>
>>previous version found Rxb2 only at depth 14
>>With verified null move pruning movei finds wac 2  at depth 12.
>>
>>[D]8/7p/5k2/5p2/p1p2P2/Pr1pPK2/1P1R3P/8 b - - 0 1
>>
>>depth=12 +0.64 b3b2
>>Nodes: 6559172 NPS: 215975
>>Time: 00:00:30.37
>>
>>depth=12 +2.67 b3b2 d2b2 c4c3 b2b6 f6g7 b6b7 g7h6 b7b6 h6h5 b6b5 c3c2 b5f5 h5g6
>>f5g5 g6h6 g5c5 d3d2 c5c6 h6h5 c6c5 h5h4 c5c2 d2d1q c2e2
>>Nodes: 17674291 NPS: 212303
>>Time: 00:01:23.25
>>
>>depth=13 +3.54 b3b2 d2b2 c4c3 b2b6 f6g7 b6b7 g7h6 b7b6 h6h5 b6b5 c3c2 b5f5 h5g6
>>f5g5 g6f6 g5c5 d3d2 c5c6 f6e7 c6c7 e7d6 c7c2 d2d1q c2e2 h7h5
>>Nodes: 30679118 NPS: 220032
>>Time: 00:02:19.43
>>
>>Uri
>
>In my program nullmove delays it 1 ply, but it is still found faster.
>It seems to find it very early, for other reasons though.
>
>with nullmove:
>
>8	6	13	25569		1...c3 2.bxc3 Rxc3 3.e4 fxe4+ 4.Kxe4 Rc4+ 5.Kf3 Kf5 6.Rxd3 Rxf4+
>7.Ke2 Rxd3
>9	6	29	79390		1...c3 2.bxc3 Rxc3 3.e4 fxe4+ 4.Kxe4 Rc4+ 5.Ke3 Kf5 6.Rxd3 Rxf4
>7.Rd6
>9	5	68	234477		1...Rxb2 2.Rxb2 c3 3.Rb6+ Ke7 4.Rc6 c2
>10	0	260	990857		1...Rxb2 2.Rxb2 c3 3.Rb6+ Kg7 4.Rb7+ Kh6 5.Rb6+ Kg7
>11	0	667	2526638		1...Rxb2 2.Rxb2 c3 3.Rb6+ Kf7 4.Rb7+ Kf6 5.Rb6+ c2 Rh6

I do not understand what is the positional advantage that it finds for white.

black has a clear positional adavnatge because black's pawns are more forward.
If it can be happy with a draw then it seems that it can see some positional
advantage for white

Uri



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