Stefan Mengel
I am a CNRS researcher at the Centre de Recherche en Informatique de Lens (CRIL).
I have defended my habilitation in computer science at Université d’Artois in December 2021, see here for my habilitation thesis. Before joining CNRS, I have spent two years as a postdoc at the Laboratoire d’Informatique de l’École Polytechnique (LIX). In 2013, I have defended a PhD at the Institute of Mathematics at the University of Paderborn under the supervision of Peter Bürgisser. The electronic version of my thesis can be found here.
Here is a short CV.
CRIL-CNRS/Université d’Artois 
Faculté des Sciences Jean Perrin
rue Jean Souvraz, S.P. 18 
F-62307 LENS Cedex 
FRANCE
Email: mengel@cril.fr
Research interest
The focus of my work lies in the intersection of computational complexity theory, algorithms and combinatorics. In particular, I am very interested in applications in database theory and artificial intelligence. I also used to work in arithmetic circuit complexity.
Publications
Journals
- Alexis de Colnet, Stefan Mengel 
Characterizing Tseitin-Formulas with Short Regular Resolution Refutations 
J. Artif. Intell. Res., 2023
 arxiv journal version 
- Stefan Mengel 
No Efficient Disjunction or Conjunction of Switch-Lists 
J. Satisf. Boolean Model. Comput., 2022
 arxiv journal version 
- Stefan Mengel, Sebastian Skritek 
Characterizing Tractability of Simple Well-Designed Pattern Trees with Projection 
Theory Comput. Syst., 2021
 arxiv journal version 
- Antoine Amarilli, Pierre Bourhis, Stefan Mengel, Matthias Niewerth 
Constant-Delay Enumeration for Nondeterministic Document Spanners 
ACM Trans. Database Syst., 2021
 arxiv journal version 
- Stefan Mengel, Romain Wallon 
Graph Width Measures for CNF-Encodings with Auxiliary Variables 
J. Artif. Intell. Res., 2020
 arxiv journal version 
- Antoine Amarilli, Pierre Bourhis, Stefan Mengel, Matthias Niewerth 
Constant-Delay Enumeration for Nondeterministic Document Spanners 
SIGMOD Rec., 2020
 arxiv journal version 
- Mike Behrisch, Miki Hermann, Stefan Mengel, Gernot Salzer 
Minimal Distance of Propositional Models 
Theory Comput. Syst., 2019
 arxiv journal version 
- Stefan Mengel 
Lower bounds on the mim-width of some graph classes 
Discrete Applied Mathematics, 2018
 arxiv journal version 
- Christian Ikenmeyer, Stefan Mengel 
On the relative power of reduction notions in arithmetic circuit complexity 
Inf. Process. Lett., 2018
 arxiv journal version 
- Florent Capelli, Arnaud Durand, Stefan Mengel 
The Arithmetic Complexity of Tensor Contraction 
Theory Comput. Syst., 2016
 arxiv journal version 
- Arnaud Durand, Stefan Mengel 
Structural Tractability of Counting of Solutions to Conjunctive Queries 
Theory Comput. Syst., 2015
 arxiv journal version 
- Arnaud Durand, Stefan Mengel 
The complexity of weighted counting for acyclic conjunctive queries 
J. Comput. Syst. Sci., 2014
 arxiv journal version 
- Jochen Harant, Stefan Senitsch 
A generalization of Tutte’s theorem on Hamiltonian cycles in planar graphs 
Discrete Mathematics, 2009
 journal version 
 
Conferences
- Karl Bringmann, Nofar Carmeli, Stefan Mengel 
Tight Fine-Grained Bounds for Direct Access on Join Queries 
SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems, PODS 2022
 arxiv conference version 
- Stefan Mengel 
Changing Partitions in Rectangle Decision Lists 
25th International Conference on Theory and Applications of Satisfiability Testing, SAT 2022
 conference version 
- Alexis de Colnet, Stefan Mengel 
Lower Bounds on Intermediate Results in Bottom-Up Knowledge Compilation 
Thirty-Sixth AAAI Conference on Artificial Intelligence, AAAI 2022
 arxiv conference version 
- Alexis de Colnet, Stefan Mengel 
A Compilation of Succinctness Results for Arithmetic Circuits 
Proceedings of the 18th International Conference on Principles of Knowledge Representation and Reasoning, KR 2021, Online event, November 3-12, 2021
 arxiv conference version 
- Alexis de Colnet, Stefan Mengel 
Characterizing Tseitin-Formulas with Short Regular Resolution Refutations 
24th International Conference on Theory and Applications of Satisfiability Testing, SAT 2021, Barcelona, Spain, July 5-9, 2021
 arxiv conference version 
- Stefan Mengel, Friedrich Slivovsky 
Proof Complexity of Symbolic QBF Reasoning 
24th International Conference on Theory and Applications of Satisfiability Testing, SAT 2021, Barcelona, Spain, July 5-9, 2021
 arxiv conference version 
- Daniel Le Berre, Pierre Marquis, Stefan Mengel, Romain Wallon 
On Irrelevant Literals in Pseudo-Boolean Constraint Learning 
Proceedings of the Twenty-Ninth International Joint Conference on Artificial Intelligence, IJCAI 2020
 arxiv conference version 
- Alexis de Colnet, Stefan Mengel 
Lower Bounds for Approximate Knowledge Compilation 
Proceedings of the Twenty-Ninth International Joint Conference on Artificial Intelligence, IJCAI 2020
 arxiv conference version 
- Stefan Mengel, Romain Wallon 
Revisiting Graph Width Measures for CNF-Encodings 
22nd International Conference Theory and Applications of Satisfiability Testing, SAT 2019, Lisbon, Portugal, July 9-12, 2019
 arxiv conference version 
- Stefan Mengel, Sebastian Skritek 
Characterizing Tractability of Simple Well-Designed Pattern Trees with Projection 
22nd International Conference on Database Theory, ICDT 2019, March 26-28, 2019, Lisbon, Portugal
 arxiv conference version 
- Antoine Amarilli, Pierre Bourhis, Stefan Mengel, Matthias Niewerth 
Constant-Delay Enumeration for Nondeterministic Document Spanners 
22nd International Conference on Database Theory, ICDT 2019, March 26-28, 2019, Lisbon, Portugal
 arxiv conference version 
- Florent Capelli, Stefan Mengel 
Tractable QBF by Knowledge Compilation 
36th International Symposium on Theoretical Aspects of Computer Science, STACS 2019, March 13-16, 2019, Berlin, Germany
 arxiv conference version 
- Antoine Amarilli, Pierre Bourhis, Stefan Mengel 
Enumeration on Trees under Relabelings 
21st International Conference on Database Theory, ICDT 2018
 arxiv conference version 
- Daniel Le Berre, Pierre Marquis, Stefan Mengel, Romain Wallon 
Pseudo-Boolean Constraints from a Knowledge Representation Perspective 
The Twenty-Seventh International Joint Conference on Artificial Intelligence, IJCAI 2018
 conference version 
- Michael Lampis, Stefan Mengel, Valia Mitsou 
QBF as an Alternative to Courcelle’s Theorem 
Theory and Applications of Satisfiability Testing - SAT 2018
 arxiv conference version 
- Antoine Amarilli, Pierre Bourhis, Louis Jachiet, Stefan Mengel 
A Circuit-Based Approach to Efficient Enumeration 
44th International Colloquium on Automata, Languages, and Programming, ICALP 2017
 arxiv conference version 
- Hubie Chen, Stefan Mengel 
The logic of counting query answers 
32nd Annual ACM/IEEE Symposium on Logic in Computer Science, LICS 2017
 arxiv conference version 
- Mike Behrisch, Miki Hermann, Stefan Mengel, Gernot Salzer 
The Next Whisky Bar 
Computer Science - Theory and Applications - 11th International Computer Science Symposium in Russia, CSR 2016
 conference version 
- Simone Bova, Florent Capelli, Stefan Mengel, Friedrich Slivovsky 
Knowledge Compilation Meets Communication Complexity 
The Twenty-Fifth International Joint Conference on Artificial Intelligence, IJCAI 2016
 conference version 
- Hubie Chen, Stefan Mengel 
Counting Answers to Existential Positive Queries: A Complexity Classification 
35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems, PODS 2016
 arxiv conference version 
- Stefan Mengel 
Parameterized Compilation Lower Bounds for Restricted CNF-Formulas 
Theory and Applications of Satisfiability Testing - SAT 2016
 arxiv conference version 
- Mike Behrisch, Miki Hermann, Stefan Mengel, Gernot Salzer 
As Close as It Gets 
WALCOM: Algorithms and Computation - 10th International Workshop, WALCOM 2016
 conference version 
- Hubie Chen, Stefan Mengel 
A Trichotomy in the Complexity of Counting Answers to Conjunctive Queries 
18th International Conference on Database Theory, ICDT 2015
 arxiv conference version 
- Mike Behrisch, Miki Hermann, Stefan Mengel, Gernot Salzer 
Give Me Another One! 
Algorithms and Computation - 26th International Symposium, ISAAC 2015
 conference version 
- Simone Bova, Florent Capelli, Stefan Mengel, Friedrich Slivovsky 
On Compiling CNFs into Structured Deterministic DNNFs 
Theory and Applications of Satisfiability Testing - SAT 2015
 conference version 
- Johann Brault-Baron, Florent Capelli, Stefan Mengel 
Understanding Model Counting for beta-acyclic CNF-formulas 
32nd International Symposium on Theoretical Aspects of Computer Science, STACS 2015
 arxiv conference version 
- Florent Capelli, Arnaud Durand, Stefan Mengel 
Hypergraph Acyclicity and Propositional Model Counting 
Theory and Applications of Satisfiability Testing - SAT 2014
 arxiv conference version 
- Arnaud Durand, Stefan Mengel 
Structural tractability of counting of solutions to conjunctive queries 
Joint 2013 EDBT/ICDT Conferences, ICDT 2013
 arxiv conference version 
- Stefan Mengel 
Arithmetic Branching Programs with Memory 
Mathematical Foundations of Computer Science 2013 - 38th International Symposium, MFCS 2013
 arxiv conference version 
- Florent Capelli, Arnaud Durand, Stefan Mengel 
The arithmetic complexity of tensor contractions 
30th International Symposium on Theoretical Aspects of Computer Science, STACS 2013
 arxiv conference version 
- Hervé Fournier, Guillaume Malod, Stefan Mengel 
Monomials in arithmetic circuits: Complete problems in the counting hierarchy 
29th International Symposium on Theoretical Aspects of Computer Science, STACS 2012
 arxiv conference version 
- Stefan Mengel 
Characterizing Arithmetic Circuit Classes by Constraint Satisfaction Problems - (Extended Abstract) 
Automata, Languages and Programming - 38th International Colloquium, ICALP 2011
 conference version 
 
Other and Preprints
- Hélène Fargier, Stefan Mengel, Jérôme Mengin 
An extended Knowledge Compilation Map for Conditional Preference Statements-based and Generalized Additive Utilities-based Languages 
preprint
 arxiv 
submitted journal version 
- Antoine Amarilli, Benny Kimelfeld, Sébastien Labbé, Stefan Mengel 
Skyline Operators for Document Spanners 
preprint
 arxiv 
accepted for ICDT 2024 
- Lorenzo Loconte, Aleksanteri M. Sladek, Stefan Mengel, Martin Trapp, Arno Solin, Nicolas Gillis, Antonio Vergari 
Subtractive Mixture Models via Squaring: Representation and Learning 
preprint
 arxiv 
accepted for ICLR 2024 
- Christoph Berkholz, Stefan Mengel, Hermann Wilhelm 
A characterization of efficiently compilable constraint languages 
preprint
 arxiv 
accepted for STACS 2024 
- Hubie Chen, Gianluigi Greco, Stefan Mengel, Francesco Scarcello 
Counting Solutions to Conjunctive Queries: Structural and Hybrid Tractability 
preprint
 arxiv 
submitted journal version 
- Stefan Mengel 
A short note on the counting complexity of conjunctive queries 
preprint
 arxiv
 
- Stefan Mengel 
Conjunctive queries, arithmetic circuits and counting complexity 
PhD thesis, Universität Paderborn, 2013
 thesis 
- Stefan Mengel 
Counting, Knowledge Compilation and Applications 
habilitation thesis, Université d’Artois, 2021
 habilitation thesis