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Subject: Re: Checks in the Qsearch

Author: Robert Hyatt

Date: 14:47:27 07/02/02

Go up one level in this thread


On July 02, 2002 at 16:06:56, Christophe Theron wrote:

>On July 02, 2002 at 15:07:31, Robert Hyatt wrote:
>
>>On July 01, 2002 at 17:34:00, Alessandro Damiani wrote:
>>
>>>On June 30, 2002 at 23:59:59, Christophe Theron wrote:
>>>
>>>>On June 30, 2002 at 12:28:32, Robert Hyatt wrote:
>>>>
>>>>>On June 29, 2002 at 14:18:53, Christophe Theron wrote:
>>>>>
>>>>>>On June 28, 2002 at 17:54:56, Keith Evans wrote:
>>>>>>
>>>>>>>On June 28, 2002 at 16:33:10, Scott Gasch wrote:
>>>>>>>
>>>>>>>>Another idea that I read from was that generating non-capturing checks in the
>>>>>>>>qsearch against a side that has had a chance to stand pat already is a waste.  I
>>>>>>>>really don't understand this idea and disagree with it.  Imagine black has had
>>>>>>>>an oppertunity to stand pat but instead plays RxN (N appears hung).  Well this
>>>>>>>>looks really good unless white then generates Qd4+ forking blacks R and K and
>>>>>>>>winning the R.  If you neglect to generate checks on a side who has already had
>>>>>>>>the chance to stand pat you let him get away with RxN and like it.  If the only
>>>>>>>>reason to add checks to the qsearch is to find mates then I agree -- checking
>>>>>>>>after a side could stand pat is wasted.  But if the goal is to improve tactical
>>>>>>>>play then I think this idea is not sound.
>>>>>>>
>>>>>>>I'll be very interested to see what responses this generates. Hsu took the time
>>>>>>>to design and implement special logic to help generate checking and check
>>>>>>>evasion moves in Deep Blue which I assume was used in qsearch. This was not a
>>>>>>>trivial undertaking - it adds both additional logic and additional interconnect.
>>>>>>>He probably had a good reason for doing it, since he could have used that time
>>>>>>>for something else like implementing a small hash table.
>>>>>>
>>>>>>
>>>>>>
>>>>>>And maybe he had no good reason to do it.
>>>>>>
>>>>>>As far as I know there are many amateur programmers here that have spent much
>>>>>>more time in trying and validating ideas (not even speaking of the commercial
>>>>>>programmers) than Hsu.
>>>>>>
>>>>>>I think Hsu and his team have done a great job in implementing a chess program
>>>>>>in a chip.
>>>>>>
>>>>>>However I think taking him and his team as a reference in chess programming is a
>>>>>>big mistake.
>>>>>>
>>>>>>As I have said, I think there are many chess programmers here who are much more
>>>>>>skilled than Hsu and his team in chess programming.
>>>>>>
>>>>>>
>>>>>>
>>>>>>    Christophe
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>Hmmm.. I would _never_ make that statement.  Have you _ever_ talked with
>>>>>Hsu or Campbell?  I suspect not because if you had, you would not think
>>>>>them quite that incapable.
>>>>
>>>>
>>>>I did not say that they are incapable. They have done things I will never be
>>>>able to do.
>>>>
>>>>However I have read their description of the Deep genealogy (the document
>>>>published last year and describing their creatures in details, in particular
>>>>their evaluation function and search algorithms).
>>>>
>>>>I think it's probably as good as or even better than having a talk with them, or
>>>>else what is the purpose of their publication?
>>>>
>>>>Their evaluation function is quite complete but far from impressive (nothing
>>>>that a good micro program doesn't do - at least nothing important).
>>>>
>>>>The job they have done on search is on the other hand poor in my opinion.
>>>>
>>>>Poor is an understatement. Given the money they have been given for the project,
>>>>the almost total lack of work on the search algorithms is a shame.
>>>>
>>>>If they knew as much as many amateur programmers nowadays, they would have
>>>>worked harder on the search. It is obvious that more work on this would have
>>>>given much, much better results.
>>>>
>>>>The problem is that they have started their project with the level of knowledge
>>>>about search algorithms that was up to date at the time of Chess 4.8.
>>>>
>>>>They have invested almost no work on search before starting to design the chips.
>>>>And since they have not invested much time on this either when they were working
>>>>on revisions of the chips, in the end they have got chips able to do the kind of
>>>>search that was great... back in the seventies.
>>>>
>>>>Their chips do a brute force search, with a few exotic (most probably
>>>>inefficient) extensions.
>>>>
>>>>Since nearly twenty years we know that brute search is vastly inferior to a good
>>>>selective search.
>>>>
>>>>They have done a great achievement with a technique that is known to be vastly
>>>>inferior.
>>>>
>>>>That leaves a bitter taste of what could have been achieved with the same
>>>>resources if they only had somebody capable enough (read: averagely skilled by
>>>>CCC's standards) on the subject of chess tree searching in their team.
>>>>
>>
>>I _still_ have a problem reading that last paragraph.  I wonder if Christophe
>>knows exactly who Murray Campbell is?  IE he wrote the _first_ difinitive paper
>>on null-move search.  He conned me into being the _first_ person to implement
>>what is now known as "PVS search" (null-window) at the 1978 ACM event (more
>>on this if you want to hear an interesting story).  Singular extensions.  a
>>2200+ chess player.  I can't imagine _anybody_ saying "if they only had
>>someone capable enough, averagely skilled by CCC standards, etc" if they
>>actually _know_ Murray...
>>
>>Murray is anything _but_ "averagely skilled by CCC standards..."
>>
>>Anything but...
>>
>>And then there is Hsu, Hoane, Thomas, Andrew, etc...
>
>
>
>Then let's say they had forgotten about null move, if you really want to find an
>excuse for them.
>
>Or that they did not have enough time to implement it?

Read the paper you mentioned.  They _did_ use null move in places, just
not like we use it.  They used it for threat extensions at least, and
perhaps in other ways if you read that paper carefully...

Singular Extensions seems to be a popular topic.  Vincent claimed it did
not work.  Could not work.  Now he depends heavily on them.  I used them
in the last version of CB.  Lang, Kittinger and who knows who else used them
in professional programs.  Bruce used them in Ferret...

Their handiwork is visible in several ways.  I would hardly declare that
just because they didn't use it in the hardware, they were dummies.  In fact,
Hsu _specifically_ mentioned that the chip design supported null-move in case
they wanted to use it...  (again, this in the paper you referenced).

>
>It's not because they are smart that I cannot point out something that they did
>wrong in my opinion.
>
>I can't comment on the topic of LSI design.
>
>On the topic of chess search algorithms, I believe I can comment.
>
>
>
>    Christophe

I believe their past publications comment heavily on this as well...



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