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Subject: Re: I just got a possible stupid idea

Author: Uri Blass

Date: 14:59:14 10/03/01

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On October 03, 2001 at 16:51:49, Torstein Hall wrote:

>On October 03, 2001 at 16:10:43, Robert Hyatt wrote:
>
>>On October 03, 2001 at 16:02:26, Torstein Hall wrote:
>>
>>>What if you run two paralelle search/chess  processes. One going very fast with
>>>very little evaluation. The other going slow, with a big evaluation. The fast
>>>one always start searching on the move calculated by the slow process with the
>>>big evaluation, just checking for big materiall loss, tactical stupidities
>>>further down the tree. If it find one, the fast process sends a message goes
>>>back to the slow process and tells it do start work on the next best move.
>>>
>>>Then you perhaps can have the best from two "worlds". Intelligent search, with
>>>no tactical blunders!
>>>
>>>Torstein
>>
>>
>>Read Jonathan Schaeffer's reports on "Sun Phoenix".  He did exactly that.
>>But he did it because he was not getting a very good distributed speedup
>>on larger numbers of processors.  So some did a normal chess search together
>>as a group, the rest ran a tactical searcher called "minix".  Minix was used
>>to refute moves chosen by the positional program.
>>
>>The problem is trying to rationalize the knowledgeable search vs the tactical
>>search.  If the tactical search says your positional move loses material, what
>>do you do?  Propose another move?  And if _that_ loses material?  The search
>>becomes hugely inefficient...
>
>If the tactical search says you lose material, of course you have to change the
>next best move, and so on. But that limit can perhaps be even more than a pawn?
>And of course if all the first moves in your oredering are very bad, it do not
>matter that much if you are not very effective. You are probably already
>loosing!
>
>Anyway, its another approach, and I find the consept intriguing.
>Can I find Jonathan Schaffer's report on Sun Phoenix on the net somewhere?
>
>Torstein

I totally dislike the idea of using fast searchers for tactics.

I believe that in theory a fast searcher should be worse in tactics because it
has no idea which lines to prune or extend and has no idea about the right order
of moves.

It is possible to get more nodes per second by not using null move or extensions
and not calculating order of moves but the program is certainly going to have a
bigger branching factor and it is going to be weaker in tactics.

My example is an extreme example but I believe that if you want an engine to be
better in tactics then doing it slower in nodes per second may be a good idea.

Uri



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