Author: Christophe Theron
Date: 18:46:09 02/21/00
Go up one level in this thread
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
>>> 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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