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                      CALL FOR PAPERS

                      CI-BD-SOQE 2026
    WORKSHOP ON CRAIG INTERPOLATION, BETH DEFINABILITY,
          AND SECOND-ORDER QUANTIFIER ELIMINATION

                FLoC 2026, Lisbon, Portugal
                      24-25 July 2026

                    Deadline: 4 May 2026

                http://2026.ci-bd.soqe.org/

GENERAL INFORMATION

   CI-BD-SOQE 2026 is a FLoC 2026 workshop and will take
   place in Lisbon, Portugal, 24-25 July 2026. It continues
   a series of previous workshops on Craig Interpolation
   (CI), Beth Definability (BD), and Second-Order Quantifier
   Elimination (SOQE):

   * Workshop on Craig Interpolation and Beth Definability
     (CIBD 2024, https://cibd.bitbucket.io/cibd2024/)
   * 4th Workshop on Interpolation: From Proofs to
     Applications (iPRA 2022, https://ipra-2022.bitbucket.io/)
   * Second Workshop on Second-Order Quantifier Elimination
     and Related Topics (SOQE 2021, http://2021.soqe.org/);
   * First Workshop on Second-Order Quantifier Elimination and
     Related Topics (SOQE 2017, http://2017.soqe.org/).

TOPICS AND AIM

   Broadly viewed, Craig Interpolation (CI), Beth
   Definability (BD), and Second-Order Quantifier
   Elimination (SOQE) concern the existence and computation
   of formulas that capture consequences or logical
   constraints under some syntactic restrictions. Since such
   existence/computation questions arise in many areas of
   computer science, CI, BD, and SOQE have been thoroughly
   investigated by different communities, which has led to a
   large number of results, from foundational issues to
   practical applications. Relevant fields include proof
   theory, model theory, proof complexity, automated
   reasoning, automata theory, knowledge representation,
   program verification and databases as well as philosophy
   and linguistics.

   Topics of interest for the workshop include, but are not
   limited to:

   * Abductive reasoning
   * Algorithms for CI, BD, SOQE and related tasks
   * Applications of CI, BD, SOQE and related techniques
   * Automating circumscription
   * Automating modal correspondence theory
   * CI and BD for specific logics
   * CI and BD in model theory
   * CI in program verification
   * Forgetting in answer set programming
   * Forgetting in knowledge representation
   * Generalizations of CI
   * Generating explanations via CI
   * Implementation of CI, BD, SOQE and related tasks
   * Ontology modularization and content extraction
   * Proof complexity and feasible interpolation
   * Proof systems for CI and BD
   * Query rewriting on the basis of CI and BD
   * Separability
   * Solving constrained Horn clauses
   * Solving formula equations
   * Uniform interpolation

   The aim of the workshop is to bring together researchers
   from the many relevant fields to exchange experiences and
   findings about approaches, techniques, ongoing research
   and important open problems. We strongly believe that CI,
   BD, and SOQE - beyond sharing a similar historical
   background - offer a common basis for fruitful
   cross-disciplinary exchange.

SUBMISSION

   We invite submissions of:

   * Works with original research, either as
     - Full paper: 10-15 pages + references, or
     - Extended abstract: 5-9 pages + references

   * Abstracts of research published elsewhere, as
     - Abstract: 1-4 pages + references

   Presentations of applications, new systems or relevant
   benchmarks are welcome.

   It is expected that accepted submissions are presented at
   the workshop by at least one of the authors.

   Submissions should be written in English, formatted with
   the CEURART style
   (https://ceur-ws.org/HOWTOSUBMIT.html#CEURART).

   Submissions must be uploaded via the submission page
   https://submissions.floc26.org/ci-bd-soqe/

   Submissions will be reviewed by the program committee,
   which will select a balanced program of high-quality
   contributions.

PROCEEDINGS

   Proceedings of the workshop will be published as CEUR
   Workshop Proceedings.

REGISTRATION

   Registration is via FLoC 2026:
   https://www.floc26.org/registration

IMPORTANT DATES

       4 May 2026: Submission deadline
      25 May 2026: Author notification
       1 June 2026: Early registration for FLoC workshops
   24-25 July 2026: CI-BD-SOQE Workshop @ FLoC 2026

ORGANIZATION

   Stefan Hetzl (TU Wien)
   Jean Christoph Jung (TU Dortmund University)
   Renate A. Schmidt (The University of Manchester)
   Christoph Wernhard (University of Potsdam)