International Workshop on Quantified Boolean Formulas and Beyond

To be held virtually as a 1/2-day event, during SAT 2021 (July 5-9, 2021) https://www.ac.tuwien.ac.at/qbf2021

Affiliated to and co-located with: Int. Conf. on Theory and Applications of Satisfiability Testing (SAT 2021) July 5-9, 2021

Quantified Boolean formulas (QBF) are an extension of propositional logic which allows for explicit quantification over propositional variables. The decision problem of QBF is PSPACE-complete, compared to the NP-completeness of the decision problem of propositional logic (SAT).

Many problems from application domains such as model checking, formal verification or synthesis are PSPACE-complete, and hence could be encoded in QBF in a natural way. Considerable progress has been made in QBF solving throughout the past years. However, in contrast to SAT, QBF is not yet widely applied to practical problems in academic or industrial settings. For example, the extraction and validation of models of (un)satisfiability of QBFs has turned out to be challenging, given that state-of-the-art solvers implement different solving paradigms.

The goal of the International Workshop on Quantified Boolean Formulas (QBF Workshop) is to bring together researchers working on theoretical and practical aspects of QBF solving. In addition to that, it addresses (potential) users of QBF in order to reflect on the state-of-the-art and to consolidate on immediate and long-term research challenges.

The workshop also welcomes work on reasoning with quantifiers in related problems, such as dependency QBF (DQBF), quantified constraint satisfaction problems (QCSP), and satisfiability modulo theories (SMT) with quantifiers.


  • May 31: Submission
  • June 7: Notification of acceptance
  • June 21: Final versions of accepted papers due
  • July 5-9: Workshop (actual date depends on SAT Conference schedule)

Please see the workshop webpage for any updates: https://www.ac.tuwien.ac.at/qbf2021


The workshop is concerned with all aspects of current research on all formalisms enriched by quantifiers, and in particular QBF. The topics of interest include (but are not limited to):

  • Applications, encodings and benchmarks with quantifiers
  • QBF Proof theory and complexity results
  • Experimental evaluations of solvers or related tools
  • Case studies illustrating the power of quantifiers
  • Certificates and proofs for QBF, QCSP, SMT with quantifiers, etc.
  • Formats of proofs and certificates
  • Implementations of proof checkers and verifiers
  • Decision procedures
  • Calculi and their relationships
  • Data structures, implementation details and heuristics
  • Pre- and inprocessing techniques
  • Structural reasoning


Submissions of extended abstracts are invited and will be managed via Easychair:

  • https://easychair.org/conferences/?conf=qbf2021

In particular, we invite the submission of extended abstracts on work that has been published already, novel unpublished work, or work in progress.

The following forms of submissions are solicited:

  • Proposals for short tutorial presentations on topics related to the workshop. Tutorial proposals will be reviewed by the PC. The number of accepted tutorials depends on the overall number of accepted papers and talks, with the aim to set up a balanced workshop program.

  • Talk abstracts reporting on already published work. Such an abstract should include an outline of the planned talk, and pointers to relevant bibliography.

  • Talk proposals presenting work that is unpublished or in progress.

  • Submissions which describe novel applications of QBF or related formalisms in various domains are particularly welcome. Additionally, this call comprises known applications which have been shown to be hard for QBF solvers in the past as well as new applications for which present QBF solvers might lack certain features still to be identified.

Each submission should have an overall length of 1-4 pages in LNCS format. Authors may decide to include an appendix with additional material. Appendices will be considered at the reviewers’ discretion.

The accepted extended abstracts will be published on the workshop webpage. The workshop does not have formal proceedings.

Authors of accepted contributions are expected to give a talk at the workshop.




  • Hubie Chen, Birkbeck, University of London
  • Florian Lonsing, Stanford University
  • Martina Seidl, JKU Linz
  • Friedrich Slivovsky, TU Wien