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Subject: Re: Mate in 7 moves - diagram

Author: Bernhard Bauer

Date: 04:33:07 09/29/00

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On September 29, 2000 at 04:48:42, Dieter Buerssner wrote:

>On September 29, 2000 at 03:08:25, Bernhard Bauer wrote:
>
>>On September 28, 2000 at 10:18:53, Dieter Buerssner wrote:
>>
>>>On September 28, 2000 at 04:26:54, Bernhard Bauer wrote:
>>>
>>>[much snipped]
>>>
>>>>My modification has also to do with null move, but I do another change.
>>>>Instead of the original statement in search.c
>>>>if (do_null && !tree->in_check[ply] && pieces
>>>>                                    && (pieces>5 || depth<421)) {
>>>>
>>>>I use the following statement
>>>>if (do_null && !tree->in_check[ply] && pieces>0 && depth>60 &&
>>>>                                    && (pieces>9 || depth>301) ) {
>>>
>>>This is interesting. The original Crafty code uses null move at the leaves of
>>>the tree, when close to the endgame. Your code uses null move at at the front of
>>>the tree. Has this shown to be better in test suites or in games?
>>>
>>>Also, you don't allow null moves at the last ply. Does this reach higher depth
>>>with the same node count?
>
>Bernhard, I really read your source snippet different, then your description.
>
>>For many pieces (pieces>5) the original Crafty code will always use null move.
>
>Yes, this is like I read the source snippet of original Crafty.
>
>>I don't use null move for the first ply hoping to get a better move ordering.
>
>But wouldn't this mean to use "&& ply > 1" instead of and "depth > 60"
>
>>If only a few pieces remain I don't do null move for the first 5 plies.
>
>Again, wouldn't this mean to use "&& ply > 5" instead of "&& depht > 301"
>
>For your description I would use:
>
>if (do_null && !tree->in_check[ply] && pieces>0
>    && ply>1 /* No null move at first ply */
>    && (pieces>9 || ply>5) /* Little material: not for the first 5 plies */
>    ) {
>
>Where is my misunderstanding?

Nowhere, it's on my side.

>Nevertheless, I think depth instead of ply seems superior, for example because
>of hash table consistency. But then your ">" seems the wrong way around.
>Remember that depth is the remaining depth, or have you changed the meaning of
>depth? I would read "depth > 60" only one ply is remaining (which could make
>sense, because there is not much you can cut off in the last ply).
>
>-- Dieter

I will look at it later, no I have to leave immediately, my daughter has to go
to the hospital.

Kind regards
Bernhard




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