Author: Robert Hyatt
Date: 17:12:02 01/05/98
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On January 05, 1998 at 19:56:33, Bruce Moreland wrote: >Augh. I was hoping to avoid a "Deep Blue is awesome" thread as well. > >All I want to know why it played ... h5, since micro programs seem to >find ... h3 pretty quickly. > >bruce No idea. there have been numerous cases of their having significant bugs. Remember that they were "new" in the parallel search arena, and believe me, with parallel searches, *anything* can happen. I remember them having bugs such as screwing up castling status so that they hated to castle, or wouldn't castle, or they would, on rare occasion, play the *worst* possible move... Parallel search bugs are difficult to predict, difficult to detect, and then nearly impossible to find. I reported a while back about the worst example I ever had. We had just won the 1983 WCCC in new york, using a really poor parallel search algorithm on a two-cpu Cray XMP. That Summer, Cray told us they would have a 4 cpu machine ready for the 1984 ACM event. I requested time for a Labor-Day weekend tournament in Mobile, Alabama, to serve as a tune-up/test for my latest (at the time) parallel search code. In the first game, Cray Blitz played a move BxP check and mate. Our opponent promptly took the bishop and we lost. Turns out there were three legal moves and we had 4 processors. Deep in the tree, when searching the replies to BxP+, 3 processors found good moves to search, the 4th said "I'm mated" and this erroneously got backed up to the root. That happened after running the entire win at chess suite with no problems, plus playing several blitz games to mate... It happens. It isn't unexpected. And it is *absolutely unpreventable*...
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