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Subject: drawishness evaluation

Author: Jay Scott

Date: 15:17:12 01/14/98


It's the last round and your program needs to win.
Either a draw or a loss will put you at the same standing.
Or, it's the last round and you can't afford to lose.
With a win or a draw, you take clear first.

Your opponent is stronger than you, and you'll be
satisfied with a draw. Or, your opponent is much weaker
and you want to try for a win even in a worse position.

Humans are pretty good at adjusting their play to the
situation. But programs tend to think that an equal
sharp position is about the same as an equal drawish
position--if they have a preference, then it's always
the same preference regardless of circumstances. Some
programs have a "contempt factor" that adjusts the value
of a forced draw, but I've never heard of a program that
tries to take into account the likelihood and importance
of an eventual draw that can't yet be seen in the search.

The problem can be solved in principle by including a
separate drawish<->sharp measurement in the evaluator.
If the pawn structure is symmetrical, the position is
more drawish; if there's one open file that all the
heavy pieces will be exchanged on, it's more drawish;
opposite color bishops are drawish in the endgame and
sharp in the middlegame; a big concentration of enemy
pieces around the king suggests sharpness; that kind
of thing. Of course it's hard to measure this accurately,
but then, it's also hard to tell whether you have
enough compensation for a pawn. Measuring drawishness
doesn't seem any more difficult than that.

Once you have a drawishness measure, you can use it to
adjust the evaluation depending on how valuable a draw
is for this game. If you need to win, then a drawish
position is similar to a losing position. If you only
need a draw, a drawish position is similar to a winning
position.

Does anybody know of a program that does something like
this? Tell us about it!

I think this would be good for getting more half points
from grandmasters and more full points from weaker opponents.
I'm puzzled why I haven't heard of a program doing it.

  Jay



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