The Language of Primitive Words in not Regular: Two Simple Proofs.
Pál Dömösi, Géza Horváth · Bulletin of the European Association for Theoretical Computer Science · 2005
In this paper we give two simple proofs to show that the language Q of all primitive words over a nontrivial alphabet is not regular. We also give two simple proofs to show the nonregularity of well-known sublanguages of Q.