Conjectures on uniquely decipherable codes (Corresp.)

A conjecture concerning the codeword compositions of uniquely decipherable codes is proposed. This conjecture is shown to be equivalent to a related conjecture of Karp about the codeword costs of uniquely decipherable codes. A set of inequalities satisfied by ali prefix-condition codes is exhibited, and it is conjectured that these inequalities are valid for all uniquely decipherable codes.