# Cyclic proofs of program termination in separation logic

Brotherston, James, Bornat, Richard ORCID: https://orcid.org/0000-0002-7261-0233 and Calcagno, Cristiano
(2008)
*Cyclic proofs of program termination in separation logic.*
ACM SIGPLAN Notices - POPL '08, 43
(1)
.
pp. 101-112.
ISSN 0362-1340
[Article]
(doi:10.1145/1328897.1328453)

## Abstract

We propose a novel approach to proving the termination of heap-manipulating programs, which combines separation logic with cyclic proof within a Hoare-style proof system.Judgements in this system express (guaranteed) termination of the program when started from a given line in the program and in a state satisfying a given precondition, which is expressed as a formula of separation logic. The proof rules of our system are of two types: logical rules that operate on preconditions; and symbolic execution rules that capture the effect of executing program commands.

Our logical preconditions employ inductively defined predicates to describe heap properties, and proofs in our system are cyclic proofs: cyclic derivations in which some inductive predicate is unfolded infinitely often along every infinite path, thus allowing us to discard all infinite paths in the proof by an infinite descent argument. Moreover, the use of this soundness condition enables us to avoid the explicit construction and use of ranking functions for termination. We also give a completeness result for our system, which is relative in that it relies upon completeness of a proof system for logical implications in separation logic. We give examples illustrating our approach, including one example for which thecorresponding ranking function is non-obvious: termination of the classical algorithm for in-place reversal of a (possibly cyclic) linked list.

Item Type: | Article |
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Research Areas: | A. > School of Science and Technology > Computer Science A. > School of Science and Technology > Computer Science > Foundations of Computing group |

Item ID: | 11141 |

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Depositing User: | Teddy ~ |

Date Deposited: | 03 Jul 2013 12:42 |

Last Modified: | 17 Dec 2019 18:07 |

URI: | https://eprints.mdx.ac.uk/id/eprint/11141 |

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