Author: James T. Walker
Date: 09:54:22 12/17/98
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On December 16, 1998 at 16:31:56, David Eppstein wrote: >On December 16, 1998 at 08:45:09, James T. Walker wrote: >> It seem as though the only "Real sacrifices" are the ones that are unsound !! > >I disagree. > >If you are talking about the long term game-theoretic value, all moves are >either correct or blunders, there is no middle ground. But in real life, we >can't see that far, and we (or our computers) have to make decisions only based >on what we (or they) can see, based on imperfect heuristics such as material >evaluation. > >If a move gives up material, and we see that it later forces checkmate or the >return of at least as much material, it's a combination not a sacrifice. The >combination may be unsound (e.g. we missed a Zwischenzug) but it's still a >combination. But, if a move gives up material, and all we see in exchange for it >is positional compensation, it's a true sacrifice. The sacrifice may or may not >be sound (may or may not have the appropriate game-theoretic value) but it's >still a sacrifice. > >With computers, it's especially easy to distinguish between a sacrifice and a >combination: look at the PV and see how the material balance at the end of the >line compares with the current position. If the material balance is worse, but >the overall eval is as good or better, then it's a true sac. But you need the >PV of the machine actually playing the game, not someone else's post-game >analysis. > >It's like the difference between a theorem and a conjecture in mathematics. >Both are statements that may or may not be true (a proof can be wrong, of >course) but one is something we think we've seen through to the end and the >other isn't. >>>>>>>>>>>>>>>>>>>>>>>>> Hello David, I was trying to be funny. :-) Guess it didn't work. Any way I like your definition of a sacrifice. Jim Walker
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