It is shown how to restrict recursion on notation in all รฟnite types so as to characterize the polynomial-time computable functions. The restrictions are obtained by using a ramiรฟed type structure, and by adding linear concepts to the lambda calculus.
Safe recursion with higher types and BCK-algebra
โ Scribed by Martin Hofmann
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 314 KB
- Volume
- 104
- Category
- Article
- ISSN
- 0168-0072
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โฆ Synopsis
In previous work the author has introduced a lambda calculus SLR with modal and linear types which serves as an extension of Bellantoni-Cook's function algebra BC to higher types. It is a step towards a functional programming language in which all programs run in polynomial time. In this paper we develop a semantics of SLR using BCK-algebras consisting of certain polynomial-time algorithms. It will follow from this semantics that safe recursion with arbitrary result type built up from N and ( as well as recursion over trees and other data structures remains within polynomial time. In its original formulation SLR supported only natural numbers and recursion on notation with รฟrst-order functional result type.
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