Author: Dave Gomboc
Date: 04:47:21 05/27/99
Go up one level in this thread
On May 27, 1999 at 07:34:15, Jeremiah Penery wrote: >On May 27, 1999 at 03:19:50, Dave Gomboc wrote: > >>On May 27, 1999 at 03:16:58, Dave Gomboc wrote: >> >>>On May 27, 1999 at 02:40:10, Peter Kappler wrote: >>> >>>> >>>>Do any of you have any useful positions that you use for debugging your >>>>hashtables? >>>> >>>>I've been trying this one, which I think is pretty well known: >>>> >>>>8/k7/3p4/p2P1p2/P2P1P2/8/8/K7 w - - bm Kb1; >>>> >>>> >>>>Supposedly only Kb1 wins, but Grok likes Kb2. After 21 plies, the score jumps >>>>above +2 as Grok sees the f5 pawn dropping. >>>> >>>>Genius 6 and Fritz 5.32 both like Kb1 and give it a winning score (+2.5 to +3.0) >>>>immediately. >>>> >>>>I've seen this problem posted often enough that I trust that Kb1 is the only >>>>winning move. So not only is Grok not finding the best move, but it seems to be >>>>misevaluating Kb2. >>>> >>>>Does anybody else have problems with this position? >>>> >>>>Thanks, >>>>Peter >>> >>>You might (hand-)generate the co-ordinate square map for this position. Then >>>you will be able to look through the analysis of your program to see where it >>>screws up from, working back from where white can pick up the f-pawn. >>> >>>Dave >> >>Argh, sorry about the double post -- unresponsive GUI. :( >> >>I wanted to add, if this is the famous Fine position, then Kb2 is also winning, >>even though it gives away the "twisted diagonal opposition", so to speak. >>Reference "Computer Chess Compendium" (Levy, ed. 1998) for more details. I >>think it's discussed in 8.2 (though I wish I could find a copy to confirm this.) >> >>Dave > >This is indeed the Fine position, however I don't think Kb2 is also winning. >Crafty, after some 40 ply search, came up with a draw score. I see no way the >white king can penetrate. > >Jeremiah Wait a second, I confused it with the situation: same position, but black to play and draw. Black has two drawing moves, though Fine an Averbakh gave the "normal-looking" move. So yeah, Kb2 = bug in software, sorry :) Dave
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