# A tag system that computes Collatz sequences (i.e. C(n) = if n is # even then n/2 else (3n+1)/2). A positive integer n is represented by the # word AA...A with n A's. Taken from http://en.wikipedia.org/wiki/Tag_system. # # A X [string] --> [string] B C # B X [string] --> [string] A # C X [string] --> [string] A A A # # Author: Tjark Weber, 2007 2 ABC BA CAAA