Structure-Guided Solution of Constrained Horn Clauses

Omer Rappoport, Orna Grumberg, Yakir Vizel

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


We present StHorn, a novel technique for solving the satisfiability problem of CHCs, which works lazily and incrementally and is guided by the structure of the set of CHCs. Our technique is driven by the idea that a set of CHCs can be solved in parts, making it an easier problem for the CHC-solver. Furthermore, solving a set of CHCs can benefit from an interpretation revealed by the solver for its subsets. Our technique is lazy in that it gradually extends the set of checked CHCs, as needed. It is incremental in the way it constructs a solution by using satisfying interpretations obtained for previously checked subsets. In order to capture the structure of the problem, we define an induced CHC hypergraph that precisely corresponds to the set of CHCs. The paths in this graph are explored and used to select the clauses to be solved. We implemented StHorn on top of two CHC-solvers, Spacer and Eldarica. Our evaluation shows that StHorn complements both tools and can solve instances that cannot be solved by the other tools. We conclude that StHorn can improve upon the state-of-the-art in CHC solving.

Original languageEnglish
Title of host publicationAutomated Technology for Verification and Analysis - 21st International Symposium, ATVA 2023, Proceedings
EditorsÉtienne André, Jun Sun
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages22
ISBN (Print)9783031453311
StatePublished - 2023
Event21st International Symposium on Automated Technology for Verification and Analysis, ATVA 2023 - Singapore, Singapore
Duration: 24 Oct 202327 Oct 2023

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume14216 LNCS


Conference21st International Symposium on Automated Technology for Verification and Analysis, ATVA 2023


  • Constrained Horn Clauses
  • Verification

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Computer Science(all)


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