Author: Bob Green
Date: 19:51:33 10/07/01
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On October 07, 2001 at 19:30:46, Bruce Moreland wrote: >On October 07, 2001 at 17:34:46, Bob Green wrote: > >>I am working on a non-chess game. <snip/> >>I am asking for some tips and tricks in construction of tablebases. <snip/> >Endgame database construction is pretty simple, but there are some gotchas that >might not be the same for your game as for chess. > >The first pass you identify conversion cases (cases where the are exactly two >pieces mapped to exactly one square) and resolve them. Ok, I don't get this. Example? Are you talking checks for symetry? If so, I have that covered. >You also identify cases >where one side has won due to what in chess is checkmate. > I read this as: 1. Find all positions where the king is checkmated or 2. Find all postitions where the king is stalemated These are the starting points. Do halfboard/diagonal rotates to remove symetrical cases. Right? >You then proceed to move backwards from there. I read this as follows: 3.a move one of your pieces from the checkmate position 3.b for each possible opponent piece, move it 4. reapeat 3a/3b for all your pieces legal to move Right? >Can one side achieve a position >that is known to be won? If so, this position is resolved. Next, can one side >not avoid a position that is lost? If so, this position is resolved. Have to admit I'm a little less clear here as to why this would happen. Probably some problem w/ 3a/3b. >You keep >going until there aren't any new positions resolved, at which point you are >done. > >If you are making a DTM chess database WTF is a DTM database, BTW? >, there are problems because you can't >simply mark a position as won if you can attain a won case. If you can convert >to a mate in 19, you can't say that this is mate in 20, because there might be a >mate in less than 20 case out there if you are still working on the "natural" >mates in less than 20. I'm actually not that keen for the "best mate." Any mate would be ok. > >Also, you might not make progress on a particular pass, but you still have to >continue, because conversions cause some gaps. The above sentance is not clear. >In some endings, there are no >mates in 90, but there are mates in 100, because of conversions to very >difficult won cases. > >I'm not sure what else you are looking for, but since I'm one of the few people >that has done this, I figured that I should say something. > >bruce As always, I appreciate your guidance Mr. Moreland. Best regards, Bob Green
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