Hello, The solution that would have the most utility would be one where the elements are generated one-by-one, loop-like, so that they can be used in the body of a loop, and to avoid the fact that even with exclusion the cardinality of the target set EX^n could be in the millions even with a full list of wc's, that is, a list containing at least one wc of every length in 2..(n-1). I don't know enough Lisp, Haskell or Qi/Prolog to know if the solutions so far can be modified to do this. The Python program is too slow for large sets.
Walter Kehowski -- http://mail.python.org/mailman/listinfo/python-list