Author: Robert Hyatt
Date: 07:29:41 10/23/99
Go up one level in this thread
On October 23, 1999 at 02:31:23, Will Singleton wrote: >On October 23, 1999 at 01:37:47, Christophe Theron wrote: > >>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. >>> > >I believe it was 1947-48, but I don't have my ICCAJ here... my Dad and Claude >used to play a lot in NY around that time. > Actually I believe you are correct. I have an autographed copy of that paper in my files... and the late 40's sounds right for when it was originally published. > >>>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 > >I do think it's interesting how the language has evolved. I'm not so sure that >we ought to be bound by what was originally intended by a particular term. >Selectivity, for example, used to mean something other than what it does today; >no one implements his program in the old sense of the word. Same goes with >razoring, cut, and others. I actually think early genius programs (and maybe current ones too) did use static forward pruning, but only on every other ply to make sure it never over- looked something the opponent might play. And we _all_ use classic forward-pruning in our quiescence search, because we arbitrarily dismiss everything but captures with no searching of any kind, which is classic forward-pruning. > >I don't know whether it's possible to get folks to agree on these definitions, >since the literature itself presents conflicts. It would be a noble experiment >to try to define the terms, however, and perhaps useful for many programmers >here. > >Will
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