Title
The computability path ordering
Abstract
This paper aims at carrying out termination proofs for simply typed higher-order calculi automatically by using ordering comparisons. To this end, we introduce the computability path ordering (CPO), a recursive relation on terms obtained by lifting a precedence on function symbols. A first version, core CPO, is essentially obtained from the higher-order recursive path ordering (HORPO) by eliminating type checks from some recursive calls and by incorporating the treatment of bound variables as in the so-called computability closure. The well-foundedness proof shows that core CPO captures the essence of computability arguments a la Tait and Girard, therefore explaining its name. We further show that no further type check can be eliminated from its recursive calls without loosing well-foundedness, but one for which we found no counter-example yet. Two extensions of core CPO are then introduced which allow one to consider: the first, higher-order inductive types; the second, a precedence in which some function symbols are smaller than application and abstraction.
Year
DOI
Venue
2015
10.2168/LMCS-11(4:3)2015
LOGICAL METHODS IN COMPUTER SCIENCE
Keywords
DocType
Volume
termination,path order,rewriting,lambda-calculus,reducibility,inductive types
Journal
11
Issue
ISSN
Citations 
4
1860-5974
9
PageRank 
References 
Authors
0.52
32
3
Name
Order
Citations
PageRank
Frédéric Blanqui129017.96
Jean-Pierre Jouannaud21921227.43
Albert Rubio322819.44