Type theory in type theory using quotient inductive types

We present an internal formalisation of a type heory with dependent types in Type Theory using a special case of higher inductive types from Homotopy Type Theory which we call quotient inductive types (QITs). Our formalisation of type theory avoids referring to preterms or a typability relation but...

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Bibliographic Details
Main Authors: Altenkirch, Thorsten, Kaposi, Ambrus
Format: Conference or Workshop Item
Published: ACM 2016
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Online Access:https://eprints.nottingham.ac.uk/31169/
Description
Summary:We present an internal formalisation of a type heory with dependent types in Type Theory using a special case of higher inductive types from Homotopy Type Theory which we call quotient inductive types (QITs). Our formalisation of type theory avoids referring to preterms or a typability relation but defines directly well typed objects by an inductive definition. We use the elimination principle to define the set-theoretic and logical predicate interpretation. The work has been formalized using the Agda system extended with QITs using postulates.