Author: Dann Corbit
Date: 13:35:44 01/30/02
Go up one level in this thread
On January 30, 2002 at 15:41:51, Uri Blass wrote: >On January 30, 2002 at 14:55:16, Dann Corbit wrote: >>On January 30, 2002 at 05:07:02, Uri Blass wrote: >>[snip] >>>and side to move that make 16 "reflections" based on the definition of having >>>practically the same position(this is not the definition of Les). >>> >>>b1 a2 a7 b8 g1 h2 h7 g8 are symmetric when there are no pawns and in all of >>>these cases you can change the side to move. >> >>In the encoding scheme that Les invented, you also *multiply* this by the number >>of ways the sliding piece can go to the solution square. >> >>Suppose that a rook can mate in 12 if he slides to the solution position. There >>are up to 13 other squares he can move to the same solution sqare from other >>than the square that he is sitting on. So in this case, there are up to 16 * 13 >>= 208 board positions that will all have a mate in (12 or better). >> >>Now, Les only saves *one* of these positions [the smallest one lexically]. All >>of the others can be generated from that one. Along with all of their key moves >>and all of their centipawn evaluations. >> >>With a queen, it is even more drastic. >> >>So that is how he saves space. Work it out for KQK and see what the savings is. > > >I am not interested in KQK > >in KQK I do not need tablebases to win. The reason I mentioned it, is it is a simple example. I think most chess programs can win this one instantly without a tablebase. >it may be more interesting if it can save significant space in endgames like KQP >vs KQ when there are a lot of draws > >saving one position and saying this is winning so 100 other positions are >winning is not going to help much here. > >I am also not interested in generating all the positions from one positions in >the set that is the smallest one. > >Practically the situation that you have is getting one position that is usually >not the smallest laxically. You get some position, form its permutation set, and find the smallest entry generated. This is the key. >I do not understand how do you get practically from this position the winning >move. The VB code Les wrote shows how to do it. Did you look at it?
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