Author: Tony Werten
Date: 23:41:00 02/21/05
Go up one level in this thread
On February 21, 2005 at 08:05:15, Uri Blass wrote: >On February 21, 2005 at 06:30:57, Tony Werten wrote: > >>On February 21, 2005 at 04:12:55, Uri Blass wrote: >> >>>On February 21, 2005 at 03:54:03, Dieter Buerssner wrote: >>> >>>>On February 20, 2005 at 18:51:41, Dieter Buerssner wrote: >>>> >>>>>On February 20, 2005 at 18:40:34, Guido wrote: >>>>> >>>>>>You are right but if I remember well there is a mate in 127 and a loss in 127 in >>>>>>kppkp and another score to add is illegal position. >>>>>>So for kppkp it is necessary at least 9 bits. You could use the illegal position >>>>>>score meaning loss in 127, as illegal positions are not possible in the game. >>>>> >>>>>Hi Guido! IIRC, 8 bits was just enough for kppkp and all 256 numbers were used. >>>>>kppkp wtm has mate in 127, btm has lost in 127, together with draw and broken >>>>>positions, this exactly fits the 256 states possible in one byte. >>>> >>>>Oops, you were right, it seems. I forgot about loss in zero. Sorry for my >>>>useless post. BTW. the max positions here give fast Q-endgame, which is draw due >>>>to 50 moves rule. >>>> >>>>Dieter >>> >>>I do not understand. >>> >>>Do you say that computers with the old tablebases evaluate the max position as >a draw instead of mate and that they are right because of the 50 move rule? >>> >> >>Nope, they evaluate the max position as a win instead of a draw and they are >>wrong because of the 50 move rule :) >> >>Tony >> >>>Uri > >I do not understand. > >How they can evaluate it as win when the table is broken because of 257 values. >Do they say mate in 0 instead of mate in 127? OK, you're talking about this specific case. I think it's basicly unknown what value will come back. It depends on the compression/ what the decompression makes from it. > >Note that from movei point of view mate in 0 can be considered by tablebase as >broken position with no change in playing strength. XiniX would consider it draw. > >I think that using tablebases to find if position is mate is very expensive way >that is not needed. Yes, that's why I don't mind that the engine doesn't differentiate between draw and checkmate. If it is a checkmate, the probecode will never be reached. Tony > >Uri
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