Verifying Graph Programs with First-Order Logic

• Published in: arXiv.org
• Main Authors: Wulandari, Gia S, Plump, Detlef
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 03.12.2020
• Subjects: Computer Science - Logic in Computer Science; Formal specifications; Logic; Nested loops; Programming languages
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2012.01662

We consider Hoare-style verification for the graph programming language GP 2. In previous work, graph properties were specified by so-called E-conditions which extend nested graph conditions. However, this type of assertions is not easy to comprehend by programmers that are used to formal specifications in standard first-order logic. In this paper, we present an approach to verify GP 2 programs with a standard first-order logic. We show how to construct a strongest liberal postcondition with respect to a rule schema and a precondition. We then extend this construction to obtain strongest liberal postconditions for arbitrary loop-free programs. Compared with previous work, this allows to reason about a vastly generalised class of graph programs. In particular, many programs with nested loops can be verified with the new calculus.