Author: Jeremiah Penery
Date: 04:34:15 05/27/99
Go up one level in this thread
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
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