What I have in mind is the efficient, <enumerated> generation of the complement S^n/WC(S^n). A good program should initialize, generate, and terminate.
T=cartprodex(S,n,WC); //initialize for all i in T do what you want with i test to see if any more terminate if not and it should do this without explicitly generating WC and then complementing. For example, if the cardinality of S is m, and the WC is just '*a*b*', with a != b, then EX(S^n):=S^n\WC(S^n) has cardinality (m-1)^(n-1)*(m+n-1). Specifically, if m=5 and n=10, then |EX|=3670016 while |S^10|=9765625, so that |EX|/|S^10| is about 0.3758. In general the program should directly generate EX from arbitrary WC. Of course, in practice the WC should themselves occur in a logically consistent manner, but let's just assume they're a given. -- http://mail.python.org/mailman/listinfo/python-list
