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Subject: Re: Open letter to prof. Irazoqui about the Braingames qualifier

Author: Robert Hyatt

Date: 08:03:36 04/29/01

Go up one level in this thread


On April 29, 2001 at 05:42:42, Uri Blass wrote:

>On April 29, 2001 at 05:08:37, Chessfun wrote:
>
>>On April 29, 2001 at 04:01:32, Uri Blass wrote:
>>
>>>On April 29, 2001 at 03:39:53, Bruce Moreland wrote:
>>>
>>>>It seems clear why it wasn't invited to participate:
>>>>
>>>>1) The organizer is going to use a multiprocessor machine.
>>>>2) Fritz and Junior run on a multiprocessor machine.
>>>>3) Tiger is known to not run on such a machine.
>>>>4) Tiger is very strong, but if it is stronger than Junior or Fritz, it's
>>>>probably not stronger by much.
>>>>5) A multiprocessor machine should produce a significant performance boost.
>>>>6) It is hoped that the event will produce an "accurate" winner.
>>>>
>>>>If you allow these points, you can make a case that Tiger on a single processor
>>>>can't be stronger than Junior or Fritz on a multi.
>>
>>>I understood that tiger can use more than one processor.
>>
>>
>>I never understood that. I took it that one could be produced.
>>
>>
>>>I guess that Tiger could earn less than Fritz or Junior because of the fact that
>>>Christophe and Ed had not enough time to optimize tiger for more than one
>>>processor but it still can earn something from more than one processor.
>>
>>
>>Assuming they are within say 20 SSDF rating points of each other on
>>equal machines which seems likely. It seems highly unlikely without
>>proper debugging and testing that the above would be true. And an
>>event such as this IMO is not the place for that testing/debugging.
>
>I believe that testing debugging can be done in a few days if the target is only
>to be practically sure that it is better than the one processor version.

Sorry, but you are badly wrong.  It takes _months_.  The bugs are hard to
find.  They will only show up infrequently (not reproducible easily) and
so forth.


>
>You only need to test it in games to see that there is no problem and to test it
>in test position to see if the 2 processor version is faster than the one
>processor version.

Don't make statements until you _write_ one.  I finished Cray Blitz (the most
recent parallel search algorithm) in 1988.  I found bugs for two years at
_least_.  When I went from 2 to 4 processors new bugs showed up.  4 to 8?
same thing.  8 to 16?  Yet again.





>
>You only needs to give the parallel version to play to see if there are problems
>in games and few days are enough to get a enough games to be sure that bugs are
>not common and usually do not happen in games.



Suppose I told you I had bugs that would show up in a given position.  But
only one of every 10,000 times the position was ran for 3 minutes?

Your debugging idea makes me (as a software engineer) cringe.  You could play
all day, every day, for a month, and still have major and serious bugs that you
had not _seen_.






>
>I guess that these tests were done but I cannot know because I am not Ed or
>Christophe.
>
>>
>>
>>>I am interesting to know how much tiger earns from more than one processor.
>>
>>
>>I doubt at this time there is an answer for that.
>>
>>
>>>If there is a parallel version it is easy to compare both versions at least in
>>>test positions and to give an estimate how much is it faster on 2 processors.
>>
>>
>>You wrote above "I understood that tiger can use more than one processor."
>>Now you have changed this to "if". And IMO the same problem existed for Enrique.
>
>I understood it from Ed's post.
>
>"I  understood it" does not mean that I am 100% sure about it and this is the
>reason for the words "if there is...".
>
>Uri



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