Ohhh I must be confusing the two! But yea, Regex is just NDAs in text form! The course I have had on it is one of my favorites! Really fun stuff

You are probably thinking of Temporal logic which allows us to model if algorithms and programs terminate etc! It can be represented by using state machines tho!

Regex is actually just a way to write (Epsilon) non determistic state automata(ε-NDA) using text! ε-NDA comes from automata theory and they are just a somewhat powerful way to describe state machines! They can kind of be seen as a stepping stone to things like Context-Free Grammars which is what language parsers use to define their language/parsers, and Turing machines! Regex is a fundamental part of computer science, and they are of course incredibly useful in string validation due to their expressive power! If you study at uni and get the chance to take a course in automata theory I recommend it! Personal favorite subject :)