NII Technical Reports
National Institute of Informatics
| Title | Types for Hereditary Permutators |
| Authors | Makoto Tatsuta |
| Abstract | This paper answers the open problem of finding a type system that characterizes hereditary permutators, which is the problem 20 in the TLCA list of open problems. First this paper shows that there does not exist such a type system by showing that the set of hereditary permutatos is not recursively enumerable. The set of positive primitive recursive functions is used to prove it. Secondly this paper gives a best-possible solution by providing a set of types such that a term has every type in the set if and only if the term is a hereditary permutator. Intersection types and the Omega type is used to handle infinite computation in lambda terms. |
| Language | English |
| Published | Nov 27, 2007 |
| Pages | 11p |
| PDF File | 07-010E.pdf |