Author: Dave Gomboc
Date: 11:41:43 08/11/99
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On August 11, 1999 at 07:59:50, blass uri wrote: >On August 11, 1999 at 05:30:47, David Blackman wrote: > >>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. > >There is a commercial program that does not consider underpromotions(Junior) > >It has no problem to continue if the opponent underpromotes but it does not >consider underpromotions in the search > >Uri So Shep's idea in another thread can be particularly useful when playing Junior, by forcing it to analyze positions where an underpromotion was not already considered (though much of the time there would be a quick cutoff anyway). Dave
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