A formalized proof of strong normalization for guarded recursive types
Paper i proceeding, 2014

We consider a simplified version of Nakano’s guarded fixed-point types in a representation by infinite type expressions, defined coinductively. Smallstep reduction is parametrized by a natural number “depth” that expresses under how many guards we may step during evaluation. We prove that reduction is strongly normalizing for any depth. The proof involves a typed inductive notion of strong normalization and a Kripke model of types in two dimensions: depth and typing context. Our results have been formalized in Agda and serve as a case study of reasoning about a language with coinductive type expressions.


Andreas Abel

Göteborgs universitet

Andrea Vezzosi

Chalmers, Data- och informationsteknik, Datavetenskap

Lecture Notes in Computer Science

0302-9743 (ISSN)

Vol. 8858 140-158


Data- och informationsvetenskap