Computer Chess Club Archives




Subject: Re: Very easy mate to solve.

Author: leonid

Date: 08:23:41 12/26/01

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>For Chest this cannot be (logically) correct.  The first thing a mate-in-N
>does, is to compute the mate-in-(N-1).  So the former cannot be faster.
>That must be a timing problem/inaccuracy.
>Do I miss something important?

Hi, Heiner!

Just look into fact that with new depth procedure of search will be changed.
Specialized files, for instance, will be at new depth. Somewhere it can bring
different search sequence and with it even better time for higher depth.

I will try, by precaution, to indicate you what I know as fact and where I am
only guessing.


When search is done for position that contain mate in 8 (8 only as example) that
in some visible minority of mates, mate in 9 will take less time. For sure I
know this for selective and "complex selective" search. Anyway, for identical
selective search, in some instances, mate in 9 can take less time that in 8.
This I have seen repeatedly for many positions, since very often I start finding
mate by selective in 13 moves and only later move to much lower level. This is
how I could compare.

My presumption:

The same is true for brute force search.

I have impression that I even saw this in the past but now, when I must say
something as sure fact, feel me not that certain. Reason for this is that brute
force finding is executed for my positions when I already know that mate existe
in it. I start searching by brute force from below (4, 5, 6...) ending my search
exactly at shortest mate.

Disgracefully, I don't keep all data from my positions that can't indicate you
those positions right now. Will try to keep this data in future positions.



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