Author: Christophe Theron
Date: 22:37:47 10/22/99
Go up one level in this thread
On October 22, 1999 at 13:08:44, Robert Hyatt wrote:
>On October 21, 1999 at 15:55:21, Jeremiah Penery wrote:
>
>>On October 21, 1999 at 12:54:47, Christophe Theron wrote:
>>
>>>
>>>But no program of today do brute force. All the good programs are highly
>>>selective.
>>>
>>>If you are not talking about "true brute force" (simple-alpha beta + QSearch) I
>>>don't know what you mean. Everything else is selective.
>>
>>We must be using different definitions. I don't consider the use of null-move,
>>for example, a selective search.
>
>
>
>A word of caution. "selective search" has a precise definition in the CS
>literature, dating all the way back to Shannon's "How to program a computer
>to play chess" in the 1950's.
>
>Selective search means, very explicitly, to generate all moves at a node in
>the tree, and then to dismiss some of those a priori without any searching of
>any kind. This is also called 'forward pruning'.
>
>The idea of selective extensions was mentioned by Shannon, in the context of
>what he called a "variable depth search" which is exactly what all of our
>extensions and null-move reductions actually accomplish.
>
>I personally don't call a "null-move search" a "selective search" because it
>is an incorrect term of a previously established term. Any more than I would
>self-define the term "ampere" to mean resistance, rather than using the more
>accepted "Ohm". I don't know of anyone doing what I would call purely
>selective search, although our q-search is a perfect example, since we toss
>out some moves with no searching of any kind, while keeping others and searching
>them deeper, all in a pretty arbitrary way.
>
>It makes more sense to keep a common vocabulary when we discuss things so that
>every post doesn't require a personalized "glossary of terms" so that we can
>communicate. :)
You are right. It is indeed better that we all use the same vocabulary (and the
idea of a glossary in the "Computer Chess Resource Center" pops up again).
But in this case, how can we call the kind of "selectivity" we get from, for
example, a null move search?
Are we going to call this "variable depth search"? It's pretty misleading I
think.
It is true that we would need some discussion about these terms. The terms
"selectivity" and "full width" are often misunderstood.
A suggestion, the null move selection could be put in the category of "dynamic
selectivity" (or dynamic pruning) instead of simply "selectivity", to emphasize
on the fact that selection is decided by a search?
What do all interested readers think?
Christophe
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