Abstract:

Let X* be the free monoid on the alphabet set X, and the concept of a transversal of the language diagram Γ(X*) is introduced. On the basis of  the relation between the transversal of language diagram Γ(X*) and maximal prefix code, i.e., a prefix code A is maximal if and only if A be a transversal of language diagram Γ(X*), some characterizations and properties of semaphore codes are given.

Key words:  maximal prefix code, transversal of language diagram Γ(X*), semaphore code