Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Meaningless Underpromotions

Author: David Blackman

Date: 02:30:47 08/11/99

Go up one level in this thread


On August 10, 1999 at 19:56:10, Marc Plum wrote:

>A while back I ran some multiple engine tournaments within the Nimzo99
>interface.  One thing that I noticed was that some  programs would make
>meaningless underpromotions.  That is, in a position where a promoted pawn would
>be immediately exchanged anyway, the computer might promote to a bishop or rook
>rather than a queen.  I had occasionally encountered the same thing in my own
>games with computers; I also found a small number of computer games like this
>when doing a database search for underpromotions.  I don't have any statistics
>to present; I'm just noting that this happens not infrequently.
>
>When a human player does this, he is probably just being whimsical, or it could
>be a psychological ploy.  I wonder, though, why a computer would do it.  Is it
>just a random thing?  Does the computer reason that losing a bishop is less bad
>than losing a queen, even though the resulting position is the same? Or do
>computers like messing with people's minds too?
>
>Marc Plum

If two different promotions transpose to the same position in all critical lines
(eg. the piece must be taken immediately either way) then most programs will
choose randomly.

This reminds me, a few years back IM Guy West was playing against my program
Desperado over the board. He reached a postion where he could promote to either
Rook or Queen and either way would work out the same. With a big smile he
promoted to a Rook. Desperado handled it ok, but lost anyway.

There are supposed to be a couple of competitive programs (but not commercial
ones i think) that can't handle underpromotion. Maybe for competitive purposes
our programs should always underpromote if it is equivalent? Or is that too
slimy?



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.