Strong normalization of lambda-bar-mu-mu-tilde-calculus with explicit substitutions
Résumé
The lambda-bar-mu-mu-tilde-calculus, defined by Curien and Herbelin, is a variant of the lambda-mu-calculus that exhibits symmetries such as terms/contexts and call-by-name/call-by-value. Since it is a symmetric, and hence a non-deterministic calculus, usual proof techniques of normalization needs some adjustments to work in this setting. Here we prove the strong normalization (SN) of simply typed lambda-bar-mu-mu-tilde-calculus with explicit substitutions. For that purpose, we first prove SN of simply typed lambda-bar-mu-mu-tilde-calculus (by a variant of the reducibility technique from Barbanera and Berardi), then we formalize a proof technique of SN via PSN (preservation of strong normalization), and we prove PSN by the perpetuality technique, as formalized by Bonelli.