On the Period of a Periodic-Finite-Type Shift

Periodic-finite-type shifts (PFTpsilas) form a class of sofic shifts that strictly contains the class of shifts of finite type (SFTpsilas). In this paper, we investigate how the notion of ldquoperiodrdquo inherent in the definition of a PFT causes it to differ from an SFT, and how the period influences the properties of a PFT.