Computer Chess Club Archives




Subject: Re: The Limits of Positional Knowledge

Author: Marc van Hal

Date: 14:17:30 11/11/99

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On November 11, 1999 at 03:37:10, Michael Neish wrote:

>I sent in a question to a while ago about how best to
>improve a newly-written Chess program, either by sharpening up its search
>routine or by programming a better positional sense.  In reply I was recommended
>to study the available source code for ideas.
>This has led me to another question.  Supposing you stubbornly insist on using
>alpha-beta, and not add any of the sophisticated embellishments that everyone
>talks about (killer move, null move, etc).  How far can you expect to go just on
>programming positional sense alone?  I ask this because it seems to me (as
>someone mentioned only last week on rgcc) that positional sense in a program is
>to a large extent only window dressing, and that the strength in a program lies
>mainly in its ability to search deep.  From my meagre experience as a Chess
>programmer it seems to me that positional sense provides nothing more than
>general pointers to the program to play sensibly.
>To Dr. Hyatt, who was one of those who replied to me: have you ever tried
>feeding nonsensical positional variables to Crafty to see how its play is
>affected?  Okay, maybe nonsensical values will ruin the evaluation function
>completely (like a value of 5,000 for putting the Queen on a1) but what about
>different weighting values from the one you use in Crafty, but still sensible?
>Won't the values that enable Crafty to search for the right move in one position
>be useless (or detrimental) in other positions?  What difference can it make for
>the Bishop to get a score of 32 instead of 30 for landing on e4?  Wouldn't
>incurring a heavy penalty for moving, say, Pawn to h5 in a front of your castled
>King prevent Crafty from playing h5 when it would be correct to do so?  You will
>of course excuse me for not having studied every single line of Crafty's code.
>Thanks for your time.
Wich program has realy positional knowledge?
I gues the answer is none only a litle but not in the long term long term plans
I tryed to do the same with Rebel Century as I did with Chessmaster givving
Rebel a higher valeu for the knight wich didn't work because Rebel did not use
the pawns to suport the fields for the knight for instance a pawn on a5 and a
Knight on c5 this is the real positional knowledge for creating strong
positional points.
Bussy with personeletys a pawn is not 1.00 as the oponent has a lot more
mobiletybut about 0.25 I saw some personeletys in a sicilian play the move Knfd7
after the move g4 wich is positionaly the best move in many cases cause it takes
way the presure a bit so black builds up a litle counterplay
I gues posional play is still far away for computer programs
I don't mean that they don't have positional knowledge at all but not in finding
by creating long term positional advantages I gues when they can do this without
a doubt the will rule and win against all gm's

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