RELatinG quALIties and quantities by resource Approximation

ended

Qualitative type systems are a widespread technique exploited in the study of programming languages. Types allow to obtain relevant information on the behaviours of programs, such as termination of the evaluation. Quantitative type systems are used to achieve additional information on complexity and resource consumption. While these two families of type systems have been deeply studied, their interaction is still far to be properly understood. Given a program typed in a qualitative way, can we extract quantitative information from it in a compositional manner? This very natural and fundamental question has not received any appropriate answer yet. REGALIA aims to answer the question, deepening our understanding of the relationship between these two kinds of type systems. In order to do so, REGALIA will further develop the theory of resource approximation, by extending Girard's approximation theorems to proofs with cuts and by establishing a translation algorithm between qualitative systems and quantitative ones. I shall then exploit these results to define modular methods to study programming languages, alternative to Tait-Girard reducibility, that will offer quantitative interpretation of relevant qualitative systems in the context of both pure and effectful computation.