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Documents authored by Biere, Armin

Document
DOI: 10.4230/LIPIcs.SAT.2023.3
CadiBack: Extracting Backbones with CaDiCaL

Authors: Armin Biere, Nils Froleyks, and Wenxi Wang

Published in: LIPIcs, Volume 271, 26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023)

Abstract
The backbone of a satisfiable formula is the set of literals that are true in all its satisfying assignments. Backbone computation can improve a wide range of SAT-based applications, such as verification, fault localization and product configuration. In this tool paper, we introduce a new backbone extraction tool called CadiBack. It takes advantage of unique features available in our state-of-the-art SAT solver CaDiCaL including transparent inprocessing and single clause assumptions, which have not been evaluated in this context before. In addition, CaDiCaL is enhanced with an improved algorithm to support model rotation by utilizing watched literal data structures. In our comprehensive experiments with a large number of benchmarks, CadiBack solves 60% more instances than the state-of-the-art backbone extraction tool MiniBones. Our tool is thoroughly tested with fuzzing, internal correctness checking and cross-checking on a large benchmark set. It is publicly available as open source, well documented and easy to extend.
Cite as

Armin Biere, Nils Froleyks, and Wenxi Wang. CadiBack: Extracting Backbones with CaDiCaL. In 26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 271, pp. 3:1-3:12, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{biere_et_al:LIPIcs.SAT.2023.3,
  author =	{Biere, Armin and Froleyks, Nils and Wang, Wenxi},
  title =	{{CadiBack: Extracting Backbones with CaDiCaL}},
  booktitle =	{26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023)},
  pages =	{3:1--3:12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-286-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{271},
  editor =	{Mahajan, Meena and Slivovsky, Friedrich},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2023.3},
  URN =		{urn:nbn:de:0030-drops-184655},
  doi =		{10.4230/LIPIcs.SAT.2023.3},
  annote =	{Keywords: Satisfiability, Backbone, Incremental Solving}
}
Document
DOI: 10.4230/LIPIcs.SAT.2023.8
IPASIR-UP: User Propagators for CDCL

Authors: Katalin Fazekas, Aina Niemetz, Mathias Preiner, Markus Kirchweger, Stefan Szeider, and Armin Biere

Published in: LIPIcs, Volume 271, 26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023)

Abstract
Modern SAT solvers are frequently embedded as sub-reasoning engines into more complex tools for addressing problems beyond the Boolean satisfiability problem. Examples include solvers for Satisfiability Modulo Theories (SMT), combinatorial optimization, model enumeration and counting. In such use cases, the SAT solver is often able to provide relevant information beyond the satisfiability answer. Further, domain knowledge of the embedding system (e.g., symmetry properties or theory axioms) can be beneficial for the CDCL search, but cannot be efficiently represented in clausal form. In this paper, we propose a general interface to inspect and influence the internal behaviour of CDCL SAT solvers. Our goal is to capture the most essential functionalities that are sufficient to simplify and improve use cases that require a more fine-grained interaction with the SAT solver than provided via the standard IPASIR interface. For our experiments, we extend CaDiCaL with our interface and evaluate it on two representative use cases: enumerating graphs within the SAT modulo Symmetries framework (SMS), and as the main CDCL(T) SAT engine of the SMT solver cvc5.
Cite as

Katalin Fazekas, Aina Niemetz, Mathias Preiner, Markus Kirchweger, Stefan Szeider, and Armin Biere. IPASIR-UP: User Propagators for CDCL. In 26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 271, pp. 8:1-8:13, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{fazekas_et_al:LIPIcs.SAT.2023.8,
  author =	{Fazekas, Katalin and Niemetz, Aina and Preiner, Mathias and Kirchweger, Markus and Szeider, Stefan and Biere, Armin},
  title =	{{IPASIR-UP: User Propagators for CDCL}},
  booktitle =	{26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023)},
  pages =	{8:1--8:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-286-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{271},
  editor =	{Mahajan, Meena and Slivovsky, Friedrich},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2023.8},
  URN =		{urn:nbn:de:0030-drops-184709},
  doi =		{10.4230/LIPIcs.SAT.2023.8},
  annote =	{Keywords: SAT, CDCL, Satisfiability Modulo Theories, Satisfiability Modulo Symmetries}
}
Document
DOI: 10.4230/LIPIcs.SAT.2023.21
Faster LRAT Checking Than Solving with CaDiCaL

Authors: Florian Pollitt, Mathias Fleury, and Armin Biere

Published in: LIPIcs, Volume 271, 26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023)

Abstract
DRAT is the standard proof format used in the SAT Competition. It is easy to generate but checking proofs often takes even more time than solving the problem. An alternative is to use the LRAT proof system. While LRAT is easier and way more efficient to check, it is more complex to generate directly. Due to this complexity LRAT is not supported natively by any state-of-the-art SAT solver. Therefore Carneiro and Heule proposed the mixed proof format FRAT which still suffers from costly intermediate translation. We present an extension to the state-of-the-art solver CaDiCaL which is able to generate LRAT natively for all procedures implemented in CaDiCaL. We further present Lrat-Trim, a tool which not only trims and checks LRAT proofs in both ASCII and binary format but also produces clausal cores and has been tested thoroughly. Our experiments on recent competition benchmarks show that our approach reduces time of proof generation and certification substantially compared to competing approaches using intermediate DRAT or FRAT proofs.
Cite as

Florian Pollitt, Mathias Fleury, and Armin Biere. Faster LRAT Checking Than Solving with CaDiCaL. In 26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 271, pp. 21:1-21:12, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{pollitt_et_al:LIPIcs.SAT.2023.21,
  author =	{Pollitt, Florian and Fleury, Mathias and Biere, Armin},
  title =	{{Faster LRAT Checking Than Solving with CaDiCaL}},
  booktitle =	{26th International Conference on Theory and Applications of Satisfiability Testing (SAT 2023)},
  pages =	{21:1--21:12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-286-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{271},
  editor =	{Mahajan, Meena and Slivovsky, Friedrich},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2023.21},
  URN =		{urn:nbn:de:0030-drops-184837},
  doi =		{10.4230/LIPIcs.SAT.2023.21},
  annote =	{Keywords: SAT solving, Proof Checking, DRAT, LRAT, FRAT}
}
Document
DOI: 10.4230/DagRep.12.10.84
Theory and Practice of SAT and Combinatorial Solving (Dagstuhl Seminar 22411)

Authors: Olaf Beyersdorff, Armin Biere, Vijay Ganesh, Jakob Nordström, and Andy Oertel

Published in: Dagstuhl Reports, Volume 12, Issue 10 (2023)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 22411 "Theory and Practice of SAT and Combinatorial Solving". The purpose of this workshop was to explore the Boolean satisfiability (SAT) problem, which plays a fascinating dual role in computer science. By the theory of NP-completeness, this problem captures thousands of important applications in different fields, and a rich mathematical theory has been developed showing that all these problems are likely to be infeasible to solve in the worst case. But real-world problems are typically not worst-case, and in recent decades exceedingly efficient algorithms based on so-called conflict-driven clause learning (CDCL) have turned SAT solvers into highly practical tools for solving large-scale real-world problems in a wide range of application areas. Analogous developments have taken place for problems beyond NP such as SAT-based optimization (MaxSAT), pseudo-Boolean optimization, satisfiability modulo theories (SMT) solving, quantified Boolean formula (QBF) solving, constraint programming, and mixed integer programming, where the conflict-driven paradigm has sometimes been added to other powerful techniques. The current state of the art in combinatorial solving presents a host of exciting challenges at the borderline between theory and practice. Can we gain a deeper scientific understanding of the techniques and heuristics used in modern combinatorial solvers and why they are so successful? Can we develop tools for rigorous analysis of the potential and limitations of these algorithms? Can computational complexity theory be extended to shed light on real-world settings that go beyond worst case? Can more powerful methods of reasoning developed in theoretical research be harnessed to yield improvements in practical performance? And can state-of-the-art combinatorial solvers be enhanced to not only solve problems, but also provide verifiable proofs of correctness for the solutions they produce? This workshop gathered leading applied and theoretical researchers working on SAT and combinatorial optimization more broadly in order to stimulate an exchange of ideas and techniques. We see great opportunities for fruitful interplay between theory and practice in these areas, as well as for technology transfer between different paradigms in combinatorial optimization, and our assessment is that this workshop demonstrated very convincingly that a more vigorous interaction has potential for major long-term impact in computer science, as well for applications in industry.
Cite as

Olaf Beyersdorff, Armin Biere, Vijay Ganesh, Jakob Nordström, and Andy Oertel. Theory and Practice of SAT and Combinatorial Solving (Dagstuhl Seminar 22411). In Dagstuhl Reports, Volume 12, Issue 10, pp. 84-105, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@Article{beyersdorff_et_al:DagRep.12.10.84,
  author =	{Beyersdorff, Olaf and Biere, Armin and Ganesh, Vijay and Nordstr\"{o}m, Jakob and Oertel, Andy},
  title =	{{Theory and Practice of SAT and Combinatorial Solving (Dagstuhl Seminar 22411)}},
  pages =	{84--105},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2023},
  volume =	{12},
  number =	{10},
  editor =	{Beyersdorff, Olaf and Biere, Armin and Ganesh, Vijay and Nordstr\"{o}m, Jakob and Oertel, Andy},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.12.10.84},
  URN =		{urn:nbn:de:0030-drops-178212},
  doi =		{10.4230/DagRep.12.10.84},
  annote =	{Keywords: Boolean satisfiability (SAT), SAT solving, computational complexity, proof complexity, combinatorial solving, combinatorial optimization, constraint programming, mixed integer linear programming}
}
Document
DOI: 10.4230/LIPIcs.SAT.2022.27
Migrating Solver State

Authors: Armin Biere, Md Solimul Chowdhury, Marijn J. H. Heule, Benjamin Kiesl, and Michael W. Whalen

Published in: LIPIcs, Volume 236, 25th International Conference on Theory and Applications of Satisfiability Testing (SAT 2022)

Abstract
We present approaches to store and restore the state of a SAT solver, allowing us to migrate the state between different compute resources, or even between different solvers. This can be used in many ways, e.g., to improve the fault tolerance of solvers, to schedule SAT problems on a restricted number of cores, or to use dedicated preprocessing tools for inprocessing. We identify a minimum viable subset of the solver state to migrate such that the loss of performance is small. We then present and implement two different approaches to state migration: one approach stores the state at the end of a solver run whereas the other approach stores the state continuously as part of the proof trace. We show that our approaches enable the generation of correct models and valid unsatisfiability proofs. Experimental results confirm that the overhead is reasonable and that in several cases solver performance actually improves.
Cite as

Armin Biere, Md Solimul Chowdhury, Marijn J. H. Heule, Benjamin Kiesl, and Michael W. Whalen. Migrating Solver State. In 25th International Conference on Theory and Applications of Satisfiability Testing (SAT 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 236, pp. 27:1-27:24, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)

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@InProceedings{biere_et_al:LIPIcs.SAT.2022.27,
  author =	{Biere, Armin and Chowdhury, Md Solimul and Heule, Marijn J. H. and Kiesl, Benjamin and Whalen, Michael W.},
  title =	{{Migrating Solver State}},
  booktitle =	{25th International Conference on Theory and Applications of Satisfiability Testing (SAT 2022)},
  pages =	{27:1--27:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-242-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{236},
  editor =	{Meel, Kuldeep S. and Strichman, Ofer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2022.27},
  URN =		{urn:nbn:de:0030-drops-167015},
  doi =		{10.4230/LIPIcs.SAT.2022.27},
  annote =	{Keywords: SAT, SMT, Cloud Computing, Serverless Computing}
}
Document
DOI: 10.4230/DagRep.5.4.98
Theory and Practice of SAT Solving (Dagstuhl Seminar 15171)

Authors: Armin Biere, Vijay Ganesh, Martin Grohe, Jakob Nordström, and Ryan Williams

Published in: Dagstuhl Reports, Volume 5, Issue 4 (2015)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 15171 "Theory and Practice of SAT Solving". The purpose of this workshop was to explore one of the most significant problems in all of computer science, namely that of computing whether formulas in propositional logic are satisfiable or not. This problem is believed to be intractable in general (by the theory of NP-completeness). However, the last two decades have seen dramatic developments in algorithmic techniques, and today so-called SAT solvers are routinely and successfully used to solve large-scale real-world instances in a wide range of application areas. A surprising aspect of this development is that the best current SAT solvers are still to a large extent based on methods from the early 1960s, which can often handle formulas with millions of variables but may also get hopelessly stuck on formulas with just a few hundred variables. The fundamental question of when SAT solvers perform well or badly, and what underlying mathematical properties of the formulas influence SAT solver performance, remains very poorly understood. Another intriguing aspect is that much stronger mathematical methods of reasoning about propositional logic formulas are known today, in particular methods based on algebra and geometry, and these methods would seem to have great potential based on theoretical studies. However, attempts at harnessing the power of such methods have conspicuously failed to deliver any significant improvements in practical performance. This workshop gathered leading researchers in applied and theoretical areas of SAT and computational complexity to stimulate an increased exchange of ideas between these two communities. We see great opportunities for fruitful interplay between theoretical and applied research in this area, and believe that this workshop showed beyond doubt that a more vigorous interaction between the two has potential for major long-term impact in computer science, as well for applications in industry.
Cite as

Armin Biere, Vijay Ganesh, Martin Grohe, Jakob Nordström, and Ryan Williams. Theory and Practice of SAT Solving (Dagstuhl Seminar 15171). In Dagstuhl Reports, Volume 5, Issue 4, pp. 98-122, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2015)

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@Article{biere_et_al:DagRep.5.4.98,
  author =	{Biere, Armin and Ganesh, Vijay and Grohe, Martin and Nordstr\"{o}m, Jakob and Williams, Ryan},
  title =	{{Theory and Practice of SAT Solving (Dagstuhl Seminar 15171)}},
  pages =	{98--122},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2015},
  volume =	{5},
  number =	{4},
  editor =	{Biere, Armin and Ganesh, Vijay and Grohe, Martin and Nordstr\"{o}m, Jakob and Williams, Ryan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.5.4.98},
  URN =		{urn:nbn:de:0030-drops-53520},
  doi =		{10.4230/DagRep.5.4.98},
  annote =	{Keywords: SAT, Boolean SAT solvers, SAT solving, conflict-driven clause learning, Gr\"{o}bner bases, pseudo-Boolean solvers, proof complexity, computational complexity, parameterized complexity}
}
Document
DOI: 10.4230/OASIcs.WCET.2013.53
The Auspicious Couple: Symbolic Execution and WCET Analysis

Authors: Armin Biere, Jens Knoop, Laura Kovács, and Jakob Zwirchmayr

Published in: OASIcs, Volume 30, 13th International Workshop on Worst-Case Execution Time Analysis (2013)

Abstract
We have recently shown that symbolic execution together with the implicit path enumeration technique can successfully be applied in the Worst-Case Execution Time (WCET) analysis of programs. Symbolic execution offers a precise framework for program analysis and tracks complex program properties by analyzing single program paths in isolation. This path-wise program exploration of symbolic execution is, however, computationally expensive, which often prevents full symbolic analysis of larger applications: the number of paths in a program increases exponentially with the number of conditionals, a situation denoted as the path explosion problem. Therefore, for applying symbolic execution in the timing analysis of programs, we propose to use WCET analysis as a guidance for symbolic execution in order to avoid full symbolic coverage of the program. By focusing only on paths or program fragments that are relevant for WCET analysis, we keep the computational costs of symbolic execution low. Our WCET analysis also profits from the precise results derived via symbolic execution. In this article we describe how use-cases of symbolic execution are materialized in the r-TuBound toolchain and present new applications of WCET-guided symbolic execution for WCET analysis. The new applications of selective symbolic execution are based on reducing the effort of symbolic analysis by focusing only on relevant program fragments. By using partial symbolic program coverage obtained by selective symbolic execution, we improve the WCET analysis and keep the effort for symbolic execution low.
Cite as

Armin Biere, Jens Knoop, Laura Kovács, and Jakob Zwirchmayr. The Auspicious Couple: Symbolic Execution and WCET Analysis. In 13th International Workshop on Worst-Case Execution Time Analysis. Open Access Series in Informatics (OASIcs), Volume 30, pp. 53-63, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{biere_et_al:OASIcs.WCET.2013.53,
  author =	{Biere, Armin and Knoop, Jens and Kov\'{a}cs, Laura and Zwirchmayr, Jakob},
  title =	{{The Auspicious Couple: Symbolic Execution and WCET Analysis}},
  booktitle =	{13th International Workshop on Worst-Case Execution Time Analysis},
  pages =	{53--63},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-54-5},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{30},
  editor =	{Maiza, Claire},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2013.53},
  URN =		{urn:nbn:de:0030-drops-41225},
  doi =		{10.4230/OASIcs.WCET.2013.53},
  annote =	{Keywords: WCET analysis, Symbolic execution, WCET refinement, Flow Facts}
}
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