Author: Uri Blass
Date: 06:37:44 02/08/04
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On February 08, 2004 at 07:24:31, José Carlos 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 > > I did it in Anubis. I wrote a function that gives me a correct eval of a KPK >position in 99% of the cases. The other 1% is solved one ply later so I wrote >some code to detect when this could happen, and then I simply force one ply more >(extension in the regular search and no stand pat cutoff in qsearch. It's hard >to figure out all possible cases, but once you got it you can code it in a few >lines, and it's faster that accessing EGTB's. > > José C. I guess that you have one function that gets 4 parameters white king, black king,white pawn,side to move and return result(win,draw or unknown and you can always in the case of unknown you always can get in one ply search position that the result is not unknown(note that function for black is not needed because it is easy to change the side to move and the squares of the pieces to get symetric position). Did you check for no errors based on tablebases or did you check it manually? Uri
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