> (Personally, I doubt this actually happened. The story is old, and I don't think chess programs would have been able to see far enough ahead for them to disco

> (Personally, I doubt this actually happened. The story is old, and I don't think chess programs would have been able to see far enough ahead for them to discover that getting an overwhelming position is the way to force the opponent to checkmate them). True, but (in the traditional minimax-alpha-beta-classic-gameplay model) you're using heuristics anyway up until you're in spitting distance of the end, and it seems plausible that if this "tweak" involved something like negating something and flipping a less-than sign (or whatever) that the heuristics were evaluating correctly but the end game evaluations were backwards. (Which contradicts the explanation but not the overall story.) It's also possible that the explanation does work even with a backwards heuristic: in the try-to-win version, I'll eliminate or downgrade one branch because my only success route would be if the opponent directly manouvres themselves to be captured, which they obviously wouldn't do; but in the try-to-lose version, I might eliminate the same branch because I expect the opponent would do that but I don't want that to happen. I can't quite fully work out the logic in my head but it seems plausible.