Author: Christophe Theron
Date: 10:09:03 02/22/00
Go up one level in this thread
On February 22, 2000 at 09:35:22, Robert Hyatt wrote:
>On February 21, 2000 at 21:46:09, Christophe Theron wrote:
>
>>On February 21, 2000 at 21:33:23, Robert Hyatt wrote:
>>
>>>On February 21, 2000 at 21:03:19, Christophe Theron wrote:
>>>
>>>>On February 21, 2000 at 16:52:03, Robert Hyatt wrote:
>>>>
>>>>>On February 21, 2000 at 13:33:58, Christophe Theron wrote:
>>>>>
>>>>>>On February 21, 2000 at 12:16:49, Tom Kerrigan wrote:
>>>>>>
>>>>>>>On February 21, 2000 at 11:37:52, Mark Taylor wrote:
>>>>>>>
>>>>>>>>An idea I had was to have a small incrmental value subtracted from the eval,
>>>>>>>>this small increment getting larger the deeper into the tree search the eval was
>>>>>>>>returned from. I had already done this for the values WON & LOST, but I
>>>>>>>
>>>>>>>This is a good idea. However, most chess programs have transposition tables. The
>>>>>>>ideas are not compatible, because ttables assume that a position's score is
>>>>>>>constant. You will probably want to have ttables instead of your penalty,
>>>>>>>because once in a while there are huge benefits to having a ttable.
>>>>>>>
>>>>>>>>What I did in the end I made the first search iteration look at positional eval
>>>>>>>>& material eval, then subsequent iterations looked at material eval only - but
>>>>>>>>this was really a cop out.
>>>>>>>
>>>>>>>Yeah, I think this just confuses things. A long time ago I think there was a
>>>>>>>program that ran on two CPUs. One CPU ran the regular evaluation function and
>>>>>>>one was material-only. They checked each other. But programs these days get
>>>>>>>along fine without material-only eval.
>>>>>>>
>>>>>>>-Tom
>>>>>>
>>>>>>
>>>>>>The very old program Tech (I think the author was Gillogly, correct my spelling
>>>>>>please, it was back in 1960) did this, but on only one processor I think.
>>>>>>
>>>>>>It played rather well, but was seriously handicaped by lack of deep positional
>>>>>>understanding.
>>>>>>
>>>>>>
>>>>>> Christophe
>>>>>
>>>>>
>>>>>No. Tech was a 1970+ program.
>>>>
>>>>
>>>>In the book "Echecs & Mips" written by Frédéric Louguet I have found: "1960:
>>>>Creation of the Tech program, first program able to compute complicated tactical
>>>>positions".
>>>>
>>>>I remember from articles written by David Levy that Tech used a deep tactical
>>>>search (whetever deep meant at that time), but that positional evaluation was
>>>>applied to the root moves only.
>>>>
>>>>I think this approach could be used by beginners in chess programming. The
>>>>program could be surprisingly strong (compared to beginner's usual programs).
>>>>
>>>>
>>>> Christophe
>>>
>>>
>>>that is correct. I thought you were talking about using two processors, one
>>>for the tactical search and one for the normal search (ie like Sun Phoenix did).
>>
>>
>>No actually I missed the point in Tom's post. I did not know about Phoenix.
>>
>>
>>
>>
>>>Tech was all about being fast, at the expense of making gross positional errors
>>>deep in the search (if you can call 3-4-5 plies 'deep'. :)
>>
>>
>>Do you remember if he was doing a QSearch, or just used a SEE to terminate the
>>search?
>>
>>
>> Christophe
>
>No I don't, but Jim and I have corresponded regularly over the past 30 years,
>and I don't mind asking. What would be fun would be to see if he still has
>source code... :)
>
>Just to see how it would play on state-of-the-art hardware.
Yes, that would be great. But I thought his search was limited to 4 plies or so.
Anyway, a PC version of this program would be a must for many collectors.
As would be a version of Machack, or even a version of the IBM704 chess program.
I don't understand this passion for old chess programs/hardware, but I admit I
love them too. I'm still delighted with ChessGenius for the Palm, which after
all is only a version of the Mephisto Roma (1987) running on slower hardware...
But I like to see it doing tactical blunders from time to time. It looks so
"human like"... And plays very well overall.
Fernando would love it too.
Christophe
>>>>> The program that did two searches was called
>>>>>"Phoenix" by Jonathan Schaeffer. He ran a normal search with several
>>>>>workstations in parallel, and a "minix" search using several more workstations
>>>>>in parallel. Minix searched deeper looking only for tactical refutations of
>>>>>the moves being considered by the normal search.
>>>>>
>>>>>Tech was a very fast, very "dumb" type technology approach, which is where
>>>>>its name came from (tech). Jim occasionally posts on r.g.c.c and can be
>>>>>reached there.
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