Author: Uri Blass
Date: 11:41:22 02/02/04
Go up one level in this thread
On February 02, 2004 at 10:15:31, Robert Hyatt wrote: >On February 01, 2004 at 18:31:20, Ed Trice wrote: > >>Hello Dr. Hyatt, >> >>>On February 01, 2004 at 17:56:18, Ed Trice wrote: >>> >>>>I am wondering if Fritz has a specific evaluation routine for indentifying drawn >>>>Rook + f + h pawns vs. Rook arrangements. In the Crafty-Hiarcs game from the >>>>last round of the tournament, it was kibitzing a draw score for quite some time. >>>> >>>>Could it be possible to encode such a large subset of knowledge into a faultess >>>>"tablebase equivalent"? Or was it making the correct prediction for an incorrect >>>>reason? >>> >>> >>>Fritz was wrong. It kibitzed 0.0 for 50 moves. But if you remove rooks, white >>>wins instantly due to distant majority/passer. Fritz 7 did not have a clue >>>about that... >> >>Thanks, I came in around move 45 or so, I did not see the earlier announcements. >> >>Given that, I am wondering to what extent some of the R+h+f vs. R knowledge can >>be encoded in a way similar to (Heinz 2003) from Advances in Computer Games 10. > >It is not hard. I have some code that seems to work, although it is not in the >current version. It fits right in with the current KRP vs KR evaluation code >that is present. It probably needs a bit more work, just like the recent >changes to the KR[BN] vs KR stuff that had an exception I had missed. R/B pawns >is not that easy to draw, so you have to catch anything that breaks it. I wrote >some test code to run thru a bunch of KR[BN] vs KR positions and summed up wins >and draws, to see where the problems are. It is not very easy to actually code >things up, although king on the edge is pretty good. But it is not perfect, as >a game we played while working on the book (against Hiarcs) showed. We were >winning, but we went into a KRB vs KRPP (we had KRB) and thought we were winning >because Hiarcs had the king on the h-file with our rook on the g-file. But we >could not ever win that game... The exceptions are a pain. :) You cannot know by evaluation if it is a win or a draw otherwise you do not need search. computer does not "think" in terms of winning but in term of score and if you have something like +1 score it does not mean winning but something like probability of 50% to win and 50% to draw. If you think that your evaluation can cause you to miss a win too much by going to KRB vs KRPP than divide the evaluation by 2 if the side with the bishop has the advantage. Uri
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