2016-04-19 Departmental seminar: Andreas Abel (Chalmers and Gothenburg University)

Tue, 14 Oct 2025 16:51:42 +0000

Andreas Abel (Chalmers and Gothenburg University)

Formal languages, coinductively formalized

Abstract

Formal languages and automata are taught to every computer science student. However, the student will most likely not see the beautiful coalgebraic foundations.

In this talk, I recapitulate how infinite trees can represent formal languages (sets of strings). I explain Agda's coinduction mechanism based on copatterns and demonstrate that it allows an elegant representation of the usual language constructions like union, concatenation, and Kleene star, with the help of Brzozowski derivatives. We will also investigate how to reason about equality of languages using bisimulation and coinductive proofs.

2016-04-19 16:00:00 UTC
LT1415