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Subject: Re: Question for Hyatt about Alpha/Beta

Author: Anthony Cozzie

Date: 06:07:17 02/06/04

Go up one level in this thread


On February 06, 2004 at 06:26:20, Uri Blass wrote:

>On February 06, 2004 at 05:54:29, Vasik Rajlich wrote:
>
>>On February 06, 2004 at 03:42:42, Uri Blass wrote:
>>
>>>On February 06, 2004 at 02:15:35, Tord Romstad wrote:
>>>
>>>>On February 05, 2004 at 15:15:47, Uri Blass wrote:
>>>>
>>>>>I think that you underestimate your engine.
>>>>>It seems to get similiar depth to crafty.
>>>>>
>>>>>For example in the following position it got depth 11 even in blitz 4+2
>>>>
>>>>Yes, 11 plies in blitz games is not unusual.  But 11 plies in Gothmog and 11
>>>>plies in Crafty is not the same.  I do much more forward pruning and depth
>>>>reductions than Bob, and fewer extensions.  In non-tactical positions like
>>>>the one you give, my qsearch is also considerably smaller than Bob's (I think).
>>>>
>>>>Tord
>>>
>>>I do not think that there is a big difference.
>>>Crafty searches bigger tree because it searches more irrelevant lines.
>>>
>>>I guess that the main advantage of Crafty relative to Gothmog when you use one
>>>processor is superior evaluation(Gothmog's evaluation is more complex but bigger
>>>is not always better and not having  bugs or some too optimistic scores of
>>>gothmog that lead to wrong sacrifices can be more important and it is possible
>>>that Gothmog can get crafty level if you only reduce the big positional scores
>>>that encourage it to sacrifice).
>>>
>>>I do not think that gothmog see less than crafty in the relevant lines(crafty
>>>has bigger tree but it proves nothing).
>>>I know that test suites are no proof but results of the gcp test suite give me
>>>the impression that cases when Gothmog can see more than crafty are not rare.
>>>
>>>Uri
>>
>>I have the theory that the greater your search resources (ie combination of time
>>and hardware), the less important is the search, and the more important is the
>>evaluation.
>
>I do not agree with that theory.
>
>For example suppose a program has no tablebases.
>
>With deep search it may not need knowledge how to win KQ vs K when with small
>search it may need the knowledge.
>
>If the hardware is fast enough the program can solve the game with only piece
>square table evaluation.
>
>Of course we are not going to see it but with good hardware evaluation what win
>is better in some endgames become unimportant because the program will not fail
>to win thanks to search.
>
>Uri

Vas's point is this (and its the same reason Zappa is a relatively weak engine
tactically):

If you are playing at 40 / 2 on a quad opteron, do you care how many WAC
positions you can solve in 1 second?

anthony



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