Author: Christophe Theron
Date: 05:36:36 08/10/98
Go up one level in this thread
On August 10, 1998 at 00:02:15, fca wrote:
>On August 09, 1998 at 20:13:56, Christophe Theron wrote:
>
>>On August 09, 1998 at 19:18:52, Robert Hyatt wrote:
>>
>>>On August 09, 1998 at 10:22:31, Christophe Theron wrote:
>>>
>>>>Thorsten talked about this, but maybe it applied to older versions of Lang's
>>>>programs. Nobody has given evidence that Genius selects differently its moves
>>>>than the opponent's, except in the very end of the lines.
>>>>
>>>>
>>>>
>>>
>>>
>>>actually, several posted a few positions where Genius appeared to show an
>>>asymmetric search. It couldn't find the key move with a very deep search,
>>>yet if you play the key move and let it play the other side, it would find that
>>>it was lost very quickly. Which lends credibility to the idea that it looks
>>>at everything for the opponent, but prunes (forward prunes) its own moves
>>>quite a bit in the right circumstances...
>>
>>
>>I remember Thorsten said he would post some of these positions, but he didn't do
>>it, or I just missed his posts.
>>
>>I would be interested to see such positions. If somebody has found such
>>examples, would he be kind enough to repost them, please?
>
>I think there is a misunderstanding here. By Bob, maybe by Thorsten and others
>too.
>
>Genius is highly "modularised." Depending on perceived game phase, a different
>evaluation module (code segment - not just a couple of variables) is used.
>
>But...
>
>Which module to use is only set at root level. Within, the same module stays
>used.
>
>So say the root move being considered would, if made, change perceived game
>phase (not necessarily a capture, but usually so, I believe). While it is
>examined - even to 32 ply depth - the lens used will still be for module x.
>However deep the search.
>
>Now the move is chosen. So module y is now used. Alas, the evaluation is
>significantly changed - i.e. Genius now "sees it" truly.
>
>This is the heart of the problem that is misdiagnosed as asymmetry (without
>denying or confirming that such asymmetry exists :-) ).
>
>Kind regards
>
>fca
What you are describing is sometimes called the "blemish effect", and is well
known by most of us, including Bob, Thorsten and me of course.
Genius has indeed some trouble evaluating a queen exchange for example. It's not
the only one in this case! Fritz5 seems to be a little bit improved in this
regard.
When Thorsten coined the idea that Genius was assymetrical, I think he wasn't
confused by the blemish effect, and really meant that some agressive pruning was
done for one side only.
The problem is that it is not easy to show. In a normal game, Genius analyzes
only its own moves. To discover the assymetry stuff you have to replay the whole
game, ask Genius to analyze both sides, and watch carefully any score swing.
Did somebody try that?
As you seem to have a close connection with Richard, maybe you could ask him?
But I guess I already know the answer:
answer = "" ;
Christophe :)
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.