Terminal Semantics for Codata Types in Intensional Martin-Löf Type Theory

Authors Benedikt Ahrens, Régis Spadotti

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Benedikt Ahrens
Régis Spadotti

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Benedikt Ahrens and Régis Spadotti. Terminal Semantics for Codata Types in Intensional Martin-Löf Type Theory. In 20th International Conference on Types for Proofs and Programs (TYPES 2014). Leibniz International Proceedings in Informatics (LIPIcs), Volume 39, pp. 1-26, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)


We study the notions of relative comonad and comodule over a relative comonad. We use these notions to give categorical semantics for the coinductive type families of streams and of infinite triangular matrices and their respective cosubstitution operations in intensional Martin-Löf type theory. Our results are mechanized in the proof assistant Coq.
  • relative comonad
  • Martin-Löf type theory
  • coinductive type
  • computer theorem proving


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