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Subject: Re: Chessknowledge Assignment & Material Value Assessment

Author: Robert Hyatt

Date: 21:16:36 04/30/01

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On April 30, 2001 at 16:38:09, Kurt Widmann wrote:

>Hallo Programmers,
>My curiosity as to any assigned value points,stems from a game Deep Shreeder vs
>The World. Where DS reached in my opinion, a positional advantage, with a
>queenside pawn majority, potentially gaining a free-outside-passed-pawn. And a
>pair of Bishops vs N&B in an open endgame type position. Plus an advantage in
>development. Could anyone please tell me (or is it confitential) what the
>evaluation points are for:
>a)Outside passed Pawn (or potentially reachable).
>b)Bishop pair in an open position. (include potential of obtaining and or
>keeping posession. Could the value points be compared to say 1 pawn = 100
>Thanks in advance.
>Regards, Kurt Widmann


Kurt:

This is non-trivial to answer.  Take (a) above.  In Crafty, (a) varies
depending on how much material is on the board, since a simple majority with
no pieces left is nearly always winning unless there is a tactical trick or
two left on the board.

The bishop pair (in my program) is also very dynamic.  Having the bishops
is good, but it is better if some pawns have been traded to create more open
lines for them.  It is also better if pawns are on both sides of the board
in the case of bishop vs knight.  And the mobility of the bishops is also
factored in.

Since both of the above factor in, and since material influences a lot of
things, it is necessarily difficult to come up with a specific number.  The
bishop pair could (say) vary from almost nothing when all 8 pawns are on the
board for both sides and the pawns are locked up so that the bishops have little
useful mobility, to something worth a pawn or a bit more if the bishops are on
an open board and are competing against two knights, for example.

If you want some hard numbers I can probably come up with them, but the
real problem I have in testing Crafty is to take positions and look at the
scores for each individual piece to make sure that things don't look too
out-of-line with what I think reality should look like.



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