Author: David Dory
Date: 02:16:04 02/08/04
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On February 08, 2004 at 04:57:13, Uri Blass wrote: >On February 07, 2004 at 18:43:59, David Dory wrote: > >>On February 07, 2004 at 18:26:00, Uri Blass wrote: >> >>>I started to work on having some evaluation about endgame and >>>I wrote something to detect draws in KP vs K. >>> >>>It does not detect every possible draw but at least hopefully when it detect >>>draw it is correct if I have no bugs. >>> >>>Tablebases is not a solution because they are too slow and I believe that >>>generally functions are better because even in case of having tablebases if I do >>>not probe them in the qsearch I may get KP vs K that I need to evaluate without >>>tablebases and I want to return correct score without looking in tablebases. >>> >>>I read that yace is using bitbases even for 4 piece endgames when the bitbases >>>give only win draw loss information and I guess that the bitbases were >>>calculated from nalimov tablebases. >>> >>>I wonder what other people do in KP vs K endgame in case of not looking in >>>tablebases(because the program does not support tablebases or because it is a >>>qsearch node). >>> >>>Do they have a special function to detect the result or do they assume that >>>cases when they get KPK in the qsearch are rare enough when they use the 5 piece >>>tablebases because in most cases they probe the tablebases earlier. >>> >>>Uri >> >>As you say, I believe most programs would access their tablebases earlier. >> >>I always applaud adding knowledge to the endgame into the program itself, >>though. Can you give an example (diagram) of a position your code fails to find >>the draw with KP vs. K ? > >The problem is not to find the draw when you already in drawn position of KP vs >K but to evaluate the leaf Kp vs K as a draw because with wrong evaluation you >may plan to go to drawn endgame and miss another move that gives better chances. > >Uri Uri, I saw your position you posted earlier. Excellent point and very clear. I was wondering if a general heuristic could be applied: "If the opposing king is within the square of the pawn, (which as we know, from any position on the board would prevent the pawn from promoting), then advance the pawn's king to protect it immediately, either directly, or using opposition (as in your example), to block out the opposing king" Great post, Uri. David
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