[M2F] Marc Zeitoun - Nested temporal hierarchies of regular languages

In this talk, we focus on unary temporal logic over words (UTL). It is known that languages definable in this logic have several equivalent characterizations based on different formalisms. Additionally, it is known that one can decide whether a regular language can be expressed in UTL.

First, I will present these various characterizations. Then, I will introduce a general approach that encompasses all known results and allows us to obtain new ones. This approach relies on the use of an "operator" whose repeated application yields a hierarchy of classes of regular languages. Finally, I will present some results about this new hierarchy, in particular its relationship with the so-called concatenation hierarchy. This is joint work with Thomas Place.