Author: Robert Hyatt
Date: 12:15:22 10/09/98
Go up one level in this thread
On October 09, 1998 at 09:56:20, blass uri wrote: > >On October 09, 1998 at 09:35:55, Robert Hyatt wrote: > >>On October 09, 1998 at 08:54:02, blass uri wrote: >> >>> >>>On October 09, 1998 at 08:10:51, blass uri wrote: >>> >>>>I think it is better to store the number of moves to win in the tablebases only >>>>if this number is divisible by 2 because otherwise you can compute the number of >>>>moves by search. >>>> >>>>Maybe it is possible practically to store it only if it is divisble by 3 or 4 (I >>>>do not know what is the speed of reading the tablebases from harddisk) >>>> >>>>Uri >>>I think it is easy to save at least 1 bit per position by this idea if in >>>positions when there is win in N when N is divisible by 2 you store win in N/2 >>>and in positions when there is a win in N when N is not divisible by 2 you store >>>a win in 1(you can discover by search that it is not truth). >>> >> >> >>this is imposible to do. KNN vs KP is a mate in over 100 moves. How do >>I separate mate in 50 from mate in 100? I certainly can't search to find >>this out... > >I mean that when you store the number N/2 you mean win in N > >you have only to search 2 plies because if you have mate in 99 >the tablebases will tell you the number 1 >You know by search that there is no mate in 2 but you have in the tablebase >mates in 98 so by searching 2 plies you can read from the tablebases the mate >in 98 after 2 plies. >Searching 2 plies and reading the tablebases after every 2 possible plies(you do >not need every 2 possible because of the alpha beta is not impossible >> >> How do I tell the difference from a mate in 49 and a mate in 48. And *that* is critical, because if I keep choosing mates in 49 I am going to draw. In fact, a mate in 49 that I think is a mate in 48 is probably exactly enough to draw if there are exactly 50 moves to the mate to start with... >> >>>By this idea you can use the same number of bits to every position. >>> >>>If you want to use different number of bits to every popsition you must add 1 >>>bit >>>to tell if the is a position with win in number of moves divisible by 2 or not. >>> >>>of course if you lose it is not important to know the number of moves. >>> >>>I use the word win and not mate because it is a mistake to use mate >>>because of the 50 move rule >>> >>>Uri >> >> >>distance to conversion has the same 50-move problem... > >why? >If the distance is more than 50 then you know it is a draw. > >Uri but if it is *less* than 50 you don't know this. Yet you can find a score that is "conversion in 30" after you have played 30 non-capturing moves and it ends up wrong there too... ie both have problems with the 50-move rule the way they are computed...
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