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Subject: Re: About debugging HashTables implementation .

Author: Robert Hyatt

Date: 13:25:02 04/15/02

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On April 14, 2002 at 14:25:25, Pat King wrote:

>On April 13, 2002 at 00:36:07, Will Singleton wrote:
>
>[99% snipped because I'm tired of seeing "Pat King said" seven replies
>after my replies have been snipped out]
>>btw, thanks for addressing this.  I think that people toss around chess terms
>>that are not well-defined, with resulting confusion.  I still think that the
>>collision term is best defined by Beal, as I have indicated.  Two hashkeys
>>competing for the same table slot, or index, colliding.  As you define it, is
>>really a bug, and should not occur; hence the term is not meaningful.
>>
>>Will
>
>Why argue about the meaning of a word, as long as that word is defined within a
>given thread?  Is not a rose as sweet, etc, etc?
>
>I don't think any of us disagree about what constitutes a bug in this thread,
>just what to call it!
>
>Pat


There are two words that are misused all the time.  "collision" and
"branching-factor".  Collision technically means just what I said.
Branching factor is _not_ something that a program can reduce. It is
very precisely defined as the "average" number of successors from any node
in the game tree.  This can't be changed unless a program does true forward-
pruning and at every node, throws out some moves without searching them in
any way...  IE the classic approach called "selective search".  Null-move
doesn't do this.  And the better term is "effective branching factor".  We
really don't have a good term to mean "two different hash signatures mapping
to the same hash table addresss" unfortunately...

Other terms are often "bent" a bit like "ply depth" (ie what is a ply
if your program doesn't count one level in the tree as one ply like Junior?)
At times, "bending" doesn't hurt.  At other times, it causes confusion.



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