Author: Tony Werten
Date: 23:57:42 04/07/03
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On April 07, 2003 at 14:28:55, Dieter Buerssner wrote: >On April 06, 2003 at 16:09:02, Tony Werten wrote: > >>For simple EGTB: >> >>After placing the white king, there are only 63 squares left, after placing the >>white king there are only 62 squares left. So the index would be calculated >>((((SQWK*64)+SQBK)*63)+SQWR) >> >>SQBK (square black king ) would be adjusted as follows: if SQBK<SQWK then >>dec(SQBK) >>SQWR would be adjusted: if SQWR<SQWK then dec(SQWR); if SQWR<SQBK then dec(SQWR) >> >>That's the trick that saves space (well, to start with) Of course it has 1 nasty >>side effect: You can go from a position to an index, but it's quite impossible >>to get the position back from an index. > >I think it is easy. No it's not. The fact that it works in my simplified example doesn't mean anything, since nobody uses this. The point was that with the Godel numbers you can get back the position very easy but the more space you save in the table, the more difficult it becomes. Tony > >SQWR = index % (64*63); >index = index - index%(64*63); >SQBK = index % 63; >SQBK = index / 64*63; > >And now readjust the decrements you did. if SQWR >= SQBK then inc(SQWR). etc. > >I think, the problem with easy reversibibility comes into play, when you have >something like knnnk, and you don't want to use tables to calculate the index >for the 3 Ns. > >Regards, >Dieter
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