Some thoughts on the possibility or well-definedness of banning specific (indecent?) contents on the net (or elsewhere): 1) All contents (files) can be seen as natural numbers. (Use your favourite encoding function.) 2) I suppose that there is a predicate indecent_p(n), which is true if n represents something indecent, false otherwise. (Some implementation of such a predicate could be a police officer arresting you upon presentation of the number to him, yielding true. :-) ) Such numbers may be called "Indecent Numbers", their "posession", "transfer", etc. be banned. 3) Every natural number n can be perceived as the encryption of every other one m (including itself) by some function enc. n = enc(m). (Proof by cardinality) Examples: Trivial enc: "If the number is n, return m." Not so trivial enc: "Take m as a one time pad to encrypt n." 4) As a consequence, every natural number can be perceived as the encryption of an Indecent Number, hence should be banned, shouldn't it? 5) The decimal representation of any irrational number (e.g. pi, e) contains the decimal representation of every natural number somewhere. (Proof by diagonalization.) Hence the algorithm for creating this decimal representation should be banned, too, shoudn't it? 6) Finally I hope this shows what great an achievement to legislation and jurisdiction such banning might become, once established. This creates a universal crime (or vice?), everybody is guilty of automatically without the tedious procedure of seeking evidence. (maybe those not knowing about numbers at all be exempt?) Virtually Yours, Rudi Raith (raith@feilmeier.de)