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Subject: Re: detecting result by evaluation in Kp vs K positions

Author: Uri Blass

Date: 01:57:13 02/08/04

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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



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