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Constructing Infinitary Quotient-Inductive Types

Accepted version
Peer-reviewed

Type

Conference Object

Change log

Abstract

This paper introduces an expressive class of quotient-inductive types, called QW-types. We show that in dependent type theory with uniqueness of identity proofs, even the infinitary case of QW-types can be encoded using the combination of inductive-inductive definitions involving strictly positive occurrences of Hofmann-style quotient types, and Abel's size types. The latter, which provide a convenient constructive abstraction of what classically would be accomplished with transfinite ordinals, are used to prove termination of the recursive definitions of the elimination and computation properties of our encoding of QW-types. The development is formalized using the Agda theorem prover.

Description

Keywords

dependent type theory, higher inductive types, inductive-inductive definitions, quotient types, sized types, category theory

Journal Title

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Conference Name

23rd International Conference on Foundations of Software Science and Computation Structures (FoSSaCS 2020)

Journal ISSN

0302-9743
1611-3349

Volume Title

12077 LNCS

Publisher

Springer International Publishing

Rights

All rights reserved
Sponsorship
EPSRC (2119809)
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