Solving Horn Clauses on Inductive Data Types Without Induction. Issue 3 (10th August 2018)

• Record Type: Journal Article
• Authors: DE ANGELIS, EMANUELE; FIORAVANTI, FABIO; PETTOROSSI, ALBERTO; PROIETTI, MAURIZIO
• Editors: Dal Palu, Alessandro; Tarau, Paul
• Is Part Of: Theory and practice of logic programming. Volume 18:Issue 3/4(2018)
• Page Start: 452
• Page End: 469
• Publication Date: 2018-08-10
• Subjects: Program verification, -- constrained Horn clauses, -- constraint logic programming, -- inductively defined data types, -- program transformation; Logic programming -- Periodicals; Artificial intelligence -- Computer programs -- Periodicals; Constraint programming (Computer science) -- Periodicals; 005.115
• DOI: 10.1017/S1471068418000157
• Languages: English
• ISSNs: 1471-0684

Abstract

Abstract: We address the problem of verifying the satisfiability of Constrained Horn Clauses (CHCs) based on theories of inductively defined data structures, such as lists and trees. We propose a transformation technique whose objective is the removal of these data structures from CHCs, hence reducing their satisfiability to a satisfiability problem for CHCs on integers and booleans. We propose a transformation algorithm and identify a class of clauses where it always succeeds. We also consider an extension of that algorithm, which combines clause transformation with reasoning on integer constraints. Via an experimental evaluation we show that our technique greatly improves the effectiveness of applying the Z3 solver to CHCs. We also show that our verification technique based on CHC transformation followed by CHC solving, is competitive with respect to CHC solvers extended with induction.