On Irrelevance and Algorithmic Equality in Predicative Type Theory

Dependently typed programs contain an excessive amount of static terms which are necessary to please the type checker but irrelevant for computation. To separate static and dynamic code, several static analyses and type systems have been put forward. We consider Pfenning's type theory with irre...

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Bibliographic Details
Published in:Logical methods in computer science Vol. 8, Issue 1
Main Authors: Abel, Andreas, Scherer, Gabriel
Format: Journal Article
Language:English
Published: Logical Methods in Computer Science e.V 01.01.2012
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ISSN:1860-5974, 1860-5974
Online Access:Get full text
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Summary:Dependently typed programs contain an excessive amount of static terms which are necessary to please the type checker but irrelevant for computation. To separate static and dynamic code, several static analyses and type systems have been put forward. We consider Pfenning's type theory with irrelevant quantification which is compatible with a type-based notion of equality that respects eta-laws. We extend Pfenning's theory to universes and large eliminations and develop its meta-theory. Subject reduction, normalization and consistency are obtained by a Kripke model over the typed equality judgement. Finally, a type-directed equality algorithm is described whose completeness is proven by a second Kripke model.
ISSN:1860-5974
1860-5974
DOI:10.2168/LMCS-8(1:29)2012