Author: Robert Hyatt
Date: 19:40:27 12/22/00
Go up one level in this thread
On December 22, 2000 at 15:52:19, Ernst A. Heinz wrote: >>On December 22, 2000 at 14:45:03, Ernst A. Heinz wrote: >> >>>>Did you look at what happens if you play a4? Your kingside gets totally >>>>shredded, starting with Qxf7+... >>> >>>Yes, true -- but then Black's King is not standing there! >>> >>>It rather seems quite safe on d8 while White's King gets >>>into mighty trouble on d1 after the sequence a4 - Qxf7+ - >>>Kd8 - Qxg7: >>> >>>[d]2rk3r/6Q1/4p3/1pqpP3/p3b1PP/1B6/PPP2R1R/2K5 b - - 0 1 >>> >>>"DarkThought" quickly scores this as substantially positive >>>for Black, locking onto Qe3+ as the best move almost instantly. >>> >>>=Ernst= >> >>I have no doubt that black might actually be winning here. But that wasn't >>the point. You said you picked a4 at depth=10. For that to happen, you have >>to ignore king safety and sit in the middle of the board, with a queen at f7, >>a rook on the open file, the king rook hanging, the king can't move to connect >>the rooks, etc. >> >>IE at 10 ply it is all judgement, not "truth" as the search probably can't see >>the final outcome. > >"DarkThought" gets a fail-low on 0-0 in iteration #10 with the >score dropping from +1.1 in iteration #9 to just +0.39. Then, >it locks onto a4 and shows the correct PV for it already in >iteration #10 (with the white King being driven to d1 where it >is similarly exposed as the black King on d8). > >So, why should that mean to ignore king safety or all the other >evaluation stuff you are talking about above? > >To me, it simply looks like our search picks up the crucial >threats earlier (maybe, by means of more appropriate extensions >in this particular case) -- no more, no less. > >=Ernst= Note that I am not saying your eval is bad, your search is bad, nor am I saying mine is right. I am simply saying that in _this_ position, your program is probably not seeing the "truth" any more than any of the other programs that have been tested on this position see it. It appears, to me, that it becomes a matter of how the evaluation is tuned. IE you fail low on castling at depth 10. Crafty likes Rc7 until depth=12 or so where it fails _high_ on castling. I seriously doubt you see more at depth=10 than I do at depth=12. I also doubt my eval is spotting something that you aren't. I do believe that we are giving different 'scores' to the same positions, and that is the deciding factor. Who is right is a good question. It seems that the programs (of various authors) are not agreeing very much...
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