Computation and reasoning: a type theory for computer science
Computation and reasoning: a type theory for computer science
TACS '97 Proceedings of the Third International Symposium on Theoretical Aspects of Computer Software
A Generic Normalisation Proof for Pure Type Systems
TYPES '96 Selected papers from the International Workshop on Types for Proofs and Programs
On Relating Type Theories and Set Theories
TYPES '98 Selected papers from the International Workshop on Types for Proofs and Programs
Proof-assistants using dependent type systems
Handbook of automated reasoning
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We introduce a pure type system (PTS) λZ with four sorts and show that this PTS captures the proof-theoretic strength of Zermelo's set theory. For that, we show that the embedding of the language of set theory into λZ via the ‘sets as pointed graphs' translation makes λZ a conservative extension of IZ+AFA+TC (intuitionistic Zermelo's set theory plus Aczel's antifoundation axiom plus the axiom of transitive closure)—a theory which is equiconsistent to Zermelo's. The proof of conservativity is achieved by defining a retraction from λZ to a (skolemised version of) Zermelo's set theory and by showing that both transformations commute via the axioms AFA and TC.