Author: Chris Whittington
Date: 02:10:27 11/25/97
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On November 25, 1997 at 02:29:28, Howard Exner wrote: >On November 24, 1997 at 13:26:16, Robert Hyatt wrote: > > >>In light of my testing, I'd simply call this a "broken" test position >>and >>throw it out. Anything but the knight sac loses outright, and most >>programs >>that can reach reasonable depth see this. I'd bet Fritz finds it quite >>quickly as well. But the solution is wrong, because the goal of the >>test >>was to test knowledge to see if a program could recognize that this is a >>draw. To do so requires an evaluation of 0.00, not -3. something, >>because >>there are plenty of -3 positions that are still dead lost. >> >>The point here, then, is only to search deeply enough to see that this >>move >>is the only way to avoid scores of -4 and worse. I ran it on Cray Blitz >>and >>it found this in 8 seconds, and liked the knight sac from then on. But >>the >>score never went above -3.8 or so, although I only let it search to >>depth=21. >>It averaged about 9.7 million nodes per second for comparison, but never >>had >>a clue that this was drawn, just that it was playing the only move that >>didn't >>lose within its horizon. (I don't have the output in front of me, but >>believe >>it found the knight sac at depth=16 or perhaps 17. I can rerun it if >>this is >>important... >> >> >>I don't count such "solutions" since I know that for every such lucky >>correct >>find, there are hundreds where such a knight sac only makes things >>easier for >>the opponent... > >Yes I agree about the knight sac could make things worse but does >that apply to the dynamics of this type of position, namely the >wrong bishop theme? What puzzles me on this position is that your >program and I assume others would avoid capturing the pawns as you >have noted. So the programs somehow "know" half the truth of this >draw. The other half would be to "know" that the captures are essential >to win. I agree. This is clearly a very interesting position that throws much light on knowledge/search debate. To 'throw it out' as Bob suggests is a travesty. Presumably allowing the one-eyed man to carry on being king in the land of the blind. But to give a 1 or a 0 for 'solving' it, is also a travesty. This is one of those positions meriting a 'describe in no less than 300 words' answer. Chris Whittington > Is it possible to code in some kind of aggressive deep search >extension for these captures. In a sense a kind of knowledge that says >"now it is the time to search deeply". > >Like you I am curious on how the "solvers" of this position >eval it. What is clear though is that Na5 is much much better than >Na1 (the only other alternative).
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