CI-BD-SOQE 2026
Workshop on Craig Interpolation, Beth Definability, and Second-Order Quantifier Elimination

FLoC 2026
Lisbon, Portugal, 24–25 July 2026

Topics and Aim Invited Speakers Submission Proceedings Registration Important Dates Program Committee Program Committee Chairs and Organizers

Topics and Aim

CI-BD-SOQE continues a series of previous workshops on Craig Interpolation, Beth Definability, and Second-Order Quantifier Elimination:

• Workshop on Craig Interpolation and Beth Definability (CIBD 2024)
• 4th Workshop on Interpolation: From Proofs to Applications (iPRA 2022)
• Second Workshop on Second-Order Quantifier Elimination and Related Topics (SOQE 2021)
• First Workshop on Second-Order Quantifier Elimination and Related Topics (SOQE 2017)

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.

Invited Speakers

TBA

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.

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.

The complete call for papers in text format suitable for posting is available from here.

Proceedings

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

Registration

Registration for the workshop is via the FLoC 2026 Registration. Note that 1 June 2026 is the deadline for early registration.

Important Dates

4 May 2026		Submission deadline
25 May 2026		Notification
1 Jun 2026		Early registration deadline for FLoC 2026 workshops
24–25 July 2026		CI-BD-SOQE Workshop @ FLoC 2026

Program Committee

TBA

Program Committee Chairs and Organizers

Stefan Hetzl		TU Wien, Austria
Jean Christoph Jung		TU Dortmund University, Germany
Renate A. Schmidt		The University of Manchester, UK
Christoph Wernhard		University of Potsdam, Germany

---