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Subject: Re: Depth vs Time

Author: Tony Werten

Date: 14:42:58 06/25/02

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On June 25, 2002 at 17:30:51, Ulrich Tuerke wrote:

>On June 25, 2002 at 02:40:59, Gian-Carlo Pascutto wrote:
>
>>On June 24, 2002 at 18:53:24, Steve Coladonato wrote:
>>
>>>>I wonder what you consider 'comparable'. There's no guarantee
>>>>they'll be similar whatsoever.
>>>
>>>That was not a well formed statement on my part.  What I meant was that for a
>>>given ply depth, the evaluation that program X comes up with should be
>>>comparable to the evaluation that program Y comes up with if both programs are
>>>fairly equal in overall strength.
>>
>>No. There is no guarantee whatsoever that this is true.
>>
>>>Therefore, if the algorithms/heuristics that
>>>program X uses allow it to get to ply M faster than program Y, then program X
>>>should win if the time allowed constrains how much time each program can use for
>>>analysis at that depth.  For example, if program X can get to ply 11 in 30 secs
>>>and program Y takes 1 min 30 secs to get there, the overall analysis that
>>>program X can generate during a game should be better than that generated by
>>>program Y and program X should win.  So it seems that the efficiency of the
>>>algorithms/heuristics will determine the overall strength of a program.
>>
>>Again, this is completely false.
>>
>>I will repeat what I said several times earlier in this thread, and that
>>is that plies are not comparable between chessprograms. The analysis of
>>one program at ply 11 can be completely different and of higher
>>quality than another at the same 11 ply. If the second program reaches
>>ply 11 faster, we have no information at all to make any solid conclusions
>>about the relative strength of those programs.
>
>Completely agreed. This integer which we are talking about should be better
>called "iteration number". It basically defines how many times the search had
>been restarted exploiting each time the results of the preceeding iteration in
>order to extend the search tree.
>IMHO, the relation of iteration number to search depth is a very loose one,
>having in mind that todays programs are heavily pruning as well as extending.
>

Hmm. I can imagine that a program that uses partial ply extensions might decide,
when the timelimit is almost reached, to start an iteration with only half a ply
deeper.

Or even worse. Every uses iterative deepening, but did anybody ever prove that
full plies are best ? Maybe 2/3 ply is better ?

Tony

>Uli
>
>>
>>--
>>GCP



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