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

Author: Uri Blass

Date: 03:03:50 11/23/02

Go up one level in this thread


On November 23, 2002 at 05:52:51, Sune Fischer wrote:

>On November 23, 2002 at 05:48:25, Uri Blass wrote:
>
>>On November 23, 2002 at 05:45:19, Sune Fischer wrote:
>>
>>>On November 23, 2002 at 05:02:40, Uri Blass wrote:
>>>
>>>>The repetition is tactics but the fact that you do not see a positive score for
>>>>other moves is evaluation.
>>>>
>>>>Movei see positive score for other moves.
>>>
>>>Other moves, you mean c3?
>>>I guess c3 is only considered at low depth where it can't see the tactics.
>>>
>>>-S.
>>
>>I mean that movei gives positive score for moves like 1...Rb8 or 1...Rb7 so it
>>is not going to be happy with 1...Rxb2 in case of a draw score.
>
>I don't see why 1..Rb8 or Rb7 should give a positive score, if you don't intend
>Rxb2! then I see no way forward for black. What is the PV?

Here is the pv of movei without verifyied null move pruning before finding Rxb2

depth=14 +0.59 b3b8 e3e4 f5e4 f3e4 b8e8 e4d4 e8e2 d4c3 e2d2 c3d2 h7h6 h2h4 h6h5
d2e3 f6e6 e3d2 e6d5
Nodes: 12019985 NPS: 188341
Time: 00:01:03.82

depth=14 +0.61 b3b6 h2h4 h7h5 d2g2 b6b7 g2d2 b7g7 e3e4 g7g1 e4e5 f6e6 d2h2 e6d5
f3e3 g1g3 e3d2
Nodes: 22524141 NPS: 184881
Time: 00:02:01.83

>
>Staticly I don't see a reason to give a high score for black, the only passed
>pawn is blocked.

protected passed pawn by a pawn is a good reason to give bonus for black even if
it is blocked.

The reason for movei are different

h2 f4 get the same score as h7 f5 by piece square table
a4 c4 d3 get better score than a3 e3 b2 based on piece square table

The black king can get into the center so it get better score than the white
king based pievce square table.

The black rook has better mobility than the white rook so black get a bonus for
better mobility.

Uri



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