Horn Clauses for Verification and Synthesis

Many Program Verification and Synthesis problems of interest can be modeled directly using Horn clauses and many recent advances in the CLP and CAV communities have centered around efficiently solving problems presented as Horn clauses.

This series of workshops aims to bring together researchers working in the communities of Constraint/Logic Programming (e.g., ICLP and CP), Program Verification (e.g., CAV, TACAS, and VMCAI), and Automated Deduction (e.g., CADE, IJCAR), on the topic of Horn clause based analysis, verification, and synthesis.

Horn clauses for verification and synthesis have been advocated by these communities in different times and from different perspectives and HCVS is organized to stimulate interaction and a fruitful exchange and integration of experiences.

The workshop follows previous meetings: HCVS 2023 in Paris (ETAPS 2023), HCVS 2022 in Munich (ETAPS 2022), HCVS 2021 in Luxembourg (online, ETAPS 2021), HCVS 2020 in Dublin, Ireland (ETAPS 2020), HCVS 2019 in Prague, Czech Republic (ETAPS 2019), HCVS 2018 in Oxford, UK (CAV, ICLP and IJCAR at FLoC 2018), HCVS 2017 in Gothenburg, Sweden (CADE 2017), HCVS 2016 in Eindhoven, The Netherlands (ETAPS 2016), HCVS 2015 in San Francisco, CA, USA (CAV 2015), and HCVS 2014 in Vienna, Austria (VSL).

Aims and Scope

Topics of interest include, but are not limited to the use of Horn clauses, constraints, and related formalisms in the following areas:

  • Analysis and verification of programs and systems of various kinds (e.g., imperative, object-oriented, functional, logic, higher-order, concurrent, transition systems, petri-nets, smart contracts)
  • Program synthesis
  • Program testing
  • Program transformation
  • Constraint solving
  • Type systems
  • Machine learning and automated reasoning
  • CHC encoding of analysis and verification problems
  • Resource analysis
  • Case studies and tools
  • Challenging problems
We solicit regular papers describing theory and implementation of Horn-clause based analysis and tool descriptions. We also solicit extended abstracts describing work-in-progress, as well as presentations covering previously published results that are of interest to the workshop.

CHC Competition

HCVS 2024 is planning to host the 7th competition on constraint Horn clauses ( CHC-COMP ), which will compare state-of-the-art tools for CHC solving for performance and effectiveness on a set of publicly available benchmarks.


Sunday, 07 April 2024 (All times are in CEST).

Room: Vianden
09:25 - 09:30 Welcome (Julie Cailler, Danier Neider)
Session 1 (Chair: Julie Cailler)
9:30 - 10:00 Accelerated Bounded Model Checking (presentation-only paper)
Florian Frohn and Jürgen Giesl  
10:00 - 10:30 Coffee Break 
Session 2 (Chair: Maurizio Proietti)
10:30 - 11:30 Towards Scalable Fully Automatic Program Verification (invited talk)
Hari Govind  
11:30 - 12:00 Boosting Constrained Horn Solving by Unsat Core Learning (presentation-only paper)
Parosh Aziz Abdulla, Chencheng Liang and Philipp Rümmer  
12:00 - 12:30 CHC Model Validation with Proof Guarantees (presentation-only paper)
Rodrigo Otoni, Martin Blicha, Patrick Eugster and Natasha Sharygina  
12:30 - 14:00 Lunch Break 
Session 3 (Chair: Daniel Neider)
14:00 - 14:30 Towards formal verification of attested TLS: Potential replay attacks on RA-TLS (presentation-only paper)
Muhammad Usama Sardar, Arto Niemi, Hannes Tschofenig and Thomas Fossati  
14:30 - 15:00 Mode-based Transformation from Satisfiability of Constrained Horn Clauses to Test-friendly Reachability Problem
Hiroyuki Katsura, Naoki Kobayashi, Ken Sakayori and Ryosuke Sato  
15:00 - 15:30 Redundancy Checking in Reversible Flowcharts by Constrained Horn Clauses
Robert Glück and Maurizio Proietti  
15:30 - 16:00 Using Horn Solvers to Generate Memory Access Permissions for Deductive Verification – A Preliminary Report
Lukas Armborst and Marieke Huisman  
16:00 - 16:30 Coffe Break 
Session 4 (Chair: Julie Cailler)
16:30 - 17:00 CHC solvers in Stainless: Work in Progress
Viktor Kunčak and Sankalp Gambhir  
17:00 - 17:30 Integration of Offline Partial Deduction and Functional Conversion for miniKanren
Aleksandr Shefer and Ekaterina Verbitskaia  
17:30 - 18:00 CHC-COMP 2024 Report
18:00 - 18:05 Closing

Program Chairs

Program Committee

  • Nikolaj Bjørner, Microsoft, USA
  • Bruno Blanchet, INRIA, France
  • Sylvain Conchon, Universite Paris-Saclay, France
  • Emanuele De Angelis, IASI-CNR, Rome, Italy
  • Gidon Ernst, Ludwig-Maximilians-Universität München (LMU Munich), Germany
  • Grigory Fedyukovich, Florida State University, USA
  • Florian Frohn, RWTH Aachen University, Germany
  • Pierre-Loic Garoche, Ludwig Maximilian University of Munich, Germany
  • Robert Glück, University of Copenhagen, Denmark
  • Hossein Hojjat, Tehran Institute for Advanced Studies, Iran
  • Bishoksan Kafle, University of Melbourne, Australia
  • Naoki Kobayashi, University of Tokyo, Japan
  • Yanhong A. Liu, Stony Brook University, USA
  • Pedro Lopez-Garcia, IMDEA Software Institute and Spanish Council for Scientific Research (CSIC), Spain
  • Dale Miller, INRIA and LIX/Institut Polytechnique de Paris, France
  • Jose F. Morales, IMDEA Software Research Institute, Spain
  • Saswat Padhi, Google LLC, USA
  • Steven Ramsay University of Bristol, England
  • Muhammad Usama Sardar, Technical University of Dresden, Germany
  • Christian Schilling, Aalborg University, Denmark
  • Takeshi Tsukada, Chiba University, Japan


Submission has to be done in one of the following formats:

  • Extended abstracts (from half to 3 pages), which describe work in progress or aim to initiate discussions.
  • Presentation-only papers, i.e., papers already submitted or presented at a conference or another workshop. Such papers can be submitted in any format, and will not be included in the workshop post-proceedings.
  • Regular papers (up to 12 pages plus bibliography in EPTCS format), which should present previously unpublished work (completed or in progress), including descriptions of research, tools, and applications.
  • Tool papers (up to 4 pages in EPTCS format), including the papers written by the CHC-COMP participants, which can outline the theoretical framework, the architecture, the usage, and experiments of the tool.
All submitted papers will be refereed by the program committee and will be selected for inclusion in the program in accordance with the referee reports. At least one author of each accepted paper will be required to attend the workshop to present the contribution. If enough regular papers are accepted, both regular papers and extended abstracts will be published electronically. The publication of a paper is not intended to preclude later publication. Full versions of extended abstracts, or substantial revisions, may later be published elsewhere.

Papers must be submitted through the EasyChair system using the web page: https://easychair.org/conferences/?conf=hcvs2024