Hostname: page-component-6766d58669-bkrcr Total loading time: 0 Render date: 2026-05-14T15:00:04.057Z Has data issue: false hasContentIssue false

Theoretical Pearls: Representing ‘undefined’ in lambda calculus

Published online by Cambridge University Press:  07 November 2008

Henk Barendregt
Affiliation:
Faculty of Mathematics and Computer Science, Catholic University Nijmegen, Toernooiveld 1, 6525 ED, The Netherlands (e-mail: henk@cs.kun.nl)
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the 'Save PDF' action button.

Let ψ be a partial recursive function (of one argument) with λ-defining term F∈Λ°. This meansThere are several proposals for what Fn⌝ should be in case ψ(n) is undefined: (1) a term without a normal form (Church); (2) an unsolvable term (Barendregt); (3) an easy term (Visser); (4) a term of order 0 (Statman).

These four possibilities will be covered by one ‘master’ result of Statman which is based on the ‘Anti Diagonal Normalization Theorem’ of Visser (1980). That ingenious theorem about precomplete numerations of Ershov is a powerful tool with applications in recursion theory, metamathematics of arithmetic and lambda calculus.

Information

Type
Articles
Copyright
Copyright © Cambridge University Press 1992
Submit a response

Discussions

No Discussions have been published for this article.