Asri-unix.444 net.chess utzoo!decvax!ucbvax!menlo70!sri-unix!Wedekind.ES@PARC-MAXC Wed Jan 6 16:05:59 1982 compact representation of chess positions I used the wrong value for (log 10)/(log 2) in my previous message. The right value makes the number of 28-Piece positions about 2^140, and my guess at the total number of reachable positions becomes about 2^150. This needs checking. It seems high given Duchess' 156-bit encoding but remember that value assumes no promotions. Tom, what is the figure in Wagner's paper? It's kind of academic anyway, if you use jim's advice (variable-length codes at the record level and the bit level). Jerry