## Abstract In this paper we show that the usual intuitionistic characterization of the decidability of the propositional function __B(x) prop__ [__x : A__], i. e. to require that the predicate (∀__x__ ∈ __A__) (__B(x)__ ∨ ¬ __B(x)__) is provable, is equivalent, when working within the framework of
Hilbert's ϵ-operator in intuitionistic type theories
✍ Scribed by John L. Bell
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 702 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0044-3050
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
We investigate Hilbert's ϵ‐calculus in the context of intuitionistic type theories, that is, within certain systems of intuitionistic higher‐order logic. We determine the additional deductive strength conferred on an intuitionistic type theory by the adjunction of closed ϵ‐terms. We extend the usual topos semantics for type theories to the ϵ‐operator and prove a completeness theorem. The paper also contains a discussion of the concept of “partially defined” ϵ‐term. MSC: 03B15, 03B20, 03G30.
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