Markus Iser

Dr. rer. nat. Markus Iser

Projects and Teaching

Open and Running Theses

  • Explaining Tree Ensembles with SAT-based Automated Reasoning (Master Thesis)
    Efficient tools for automated reasoning are key to some of the most promising rigorous approaches to the explainability of machine-learned (ML) models and thus a central component of the yet young, but rapidly growing field of explainable artificial intelligence (XAI). Despite their problem-solving capabilities, ML models often suffer from opacity, making their inner workings difficult for humans to understand. Developing ways to explain the decisions made by an ML model in a way that humans can understand helps to increase confidence in AI systems beyond their pure predictive accuracy and robustness. The trustworthiness of AI systems is of paramount importance in safety-critical and high-risk applications such as law enforcement and criminal justice, critical infrastructure operations, biometric identification and categorization of natural persons, autonomous vehicles such as self-driving cars or drones, or in healthcare diagnostics and medical devices [2]. SAT-based automated reasoning for XAI helps to debug AI systems, prevent accidents, ensure that AI systems are not used in a discriminatory manner, and facilitates human supervision in collaborative human/AI teams [1].
    [1] From Contrastive to Abductive Explanations and Back Again, Ignatiev et al., 2021
    [2] Explanation in artificial intelligence: Insights from the social sciences, Miller, 2019

  • Localized Clause Scores for Parallel SAT Solvers (Bachelor Thesis)
    The scoring of clauses with the help of heuristics plays an important role in clause-learning SAT solvers. In sequential SAT solvers, such scoring heuristics decide in periodic cleanup steps which of the learned clauses are forgotten. In parallel SAT solver portfolios, such heuristics are also used when clauses are exchanged between solvers to decide which clauses to reject. Heuristics for ranking clauses primarily consider how much a learned clause restricts the search space, such as the size-heuristic, which favors short clause lengths. Modern heuristics like LBD and Activity for sequential CDCL solvers take into account the current state and course of the search. Using these heuristics in parallel SAT solvers is not necessarily meaningful due to the state dependency, i.e. at the time of sharing, a clause can be important in one solver but useless in another solver. The aim of this master thesis is to store the search state and course of all solvers of a parallel SAT solver portfolio in such a way that externally learned clauses can be re-evaluated locally and discarded if necessary.

  • Data-Driven Automatic and Optimal Evaluation of SAT Solvers (Bachelor / Master Thesis)
    The project was successfully completed by Tobias Fuchs (see original project description) and resulted in a publication. Further projects based on this are possible and can be discussed and defined on request.

  • Fast and Optimal Compression Algorithms for Propositional Models (Bachelor Thesis)
    The task is to compress propositional models, i.e. satisfying assignments to the variables in a propositional formula. Compression can be achieved by not saving variable values that can be derived from the formula and other values by unit propagation. The aim of this thesis is to implement efficient (de-)compression algorithms, to evaluate their efficiency and to evaluate different heuristics for variable ordering with respect to the resulting compressed model sizes.

Courses

Title Type Semester
Fortgeschrittene Themen im SAT Solving Seminar WS 2023/24
SAT Solving in der Praxis Lecture and Exercises SS 2023
Fortgeschrittene Themen im SAT Solving (renamed from "Scalability and Diversification in Modern SAT Solving") Seminar WS 2022/23
Practical SAT Solving Lecture and Exercises SS 2022
Automating SAT Solver Research Praxis der Forschung SS 2022
Animating Propositional Proofs Praxis der Softwareentwicklung WS 2021/22
Automating SAT Solver Research Praxis der Forschung WS 2021/22
Scalability and Diversification in Modern SAT Solving Seminar WS 2021/22
Practical SAT Solving Lecture and Exercises SS 2021
Scalability and Diversification in Modern SAT Solving Seminar WS 2020/21
Practical SAT Solving Lecture and Exercises SS 2020
SAT Community Karlsruhe (SACK) Seminar WS 2019/20
Algorithms 1 Exercises and Lecture Organization SS 2019
Algorithms 1 Exercises and Lecture Organization SS 2018
Programming Exercises and Lecture Organization WS 2013/14
Programming Exercises and Lecture Organization WS 2012/13

Publications

Title Authors Publication Year
Oracle-Based Local Search for Pseudo-Boolean Optimization Markus Iser, Jeremias Berg, Matti Järvisalo Proceedings of the 26th European Conference on Artificial Intelligence (ECAI 2023) 2023
Proceedings of SAT Competition 2023: Solver, Benchmark and Proof Checker Descriptions Editors: Tomáš Balyo, Marijn Heule, Markus Iser, Matti Järvisalo, Martin Suda University of Helsinki, Department of Computer Science 2023
Active Learning for SAT Solver Benchmarking Tobias Fuchs, Jakob Bach, Markus Iser International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS 2023) 2023
A Comprehensive Study of k-Portfolios of Recent SAT Solvers Jakob Bach, Markus Iser, Klemens Böhm International Conference on Theory and Applications of Satisfiability Testing (SAT 2022) 2022
Dinosat: A SAT Solver with Native DNF Support Thomas Bartel, Tomáš Balyo, Markus Iser Pragmatics of SAT (POS 2022) 2022
SATViz: Real-Time Visualization of Clausal Proofs Tim Holzenkamp, Kevin Kuryshev, Thomas Oltmann, Lucas Wäldele,
Johann Zuber, Tobias Heuer, and Markus Iser
Pragmatics of SAT (POS 2022) 2022
Unit Propagation with Stable Watches (+Video) Markus Iser, Tomáš Balyo 27th International Conference on Principles and Practice of Constraint Programming (CP 2021) 2021
Fast Approximate Calculation of Valid Domains in a Satisfiability-based Product Configurator Johannes Werner, Tomáš Balyo, Markus Iser, Michael Klein 23rd Configuration Workshop (ConfWS 2021) 2021
SAT Competition 2020 Nils Froleyks, Marijn Heule, Markus Iser, Matti Järvisalo, Martin Suda Artificial Intelligence Journal (AIJ) 2021
Collaborative Management of Benchmark Instances and their Attributes Markus Iser, Luca Springer, Carsten Sinz arXiv preprint 2020
Proceedings of SAT Competition 2020: Solver and Benchmark Descriptions Editors: Tomáš Balyo, Nils Froleyks, Marijn Heule, Markus Iser, Matti Järvisalo, Martin Suda University of Helsinki, Department of Computer Science 2020
Recognition and Exploitation of Gate Structure in SAT Solving (Dissertation) Markus Iser Karlsruhe Institute of Technology, Germany 2020
Memory Efficient Parallel SAT Solving with Inprocessing Markus Iser, Tomáš Balyo, Carsten Sinz IEEE 31st International Conference on Tools with Artificial Intelligence (ICTAI 2019) 2019
Candy for SAT Race 2019 Markus Iser, Felix Kutzner SAT RACE 2019 2019
Systematic Analysis of Experiments in Solving Boolean Satisfiability Problems Markus Iser Deduktionstreffen 2019
Integrating Static Code Analysis Toolchains Matthias Kern, Ferhat Erata, Markus Iser, Carsten Sinz, Frederic Loiret, Stefan Otten, Eric Sax IEEE 43rd Annual Computer Software and Applications Conference (COMPSAC) 2019
A Problem Meta-Data Library for Research in SAT Markus Iser, Carsten Sinz Proceedings of Pragmatics of SAT 2019
Using Gate Recognition and Random Simulation for Under-Approximation and Optimized Branching in SAT Solvers Markus Iser, Felix Kutzner, Carsten Sinz IEEE 29th International Conference on Tools with Artificial Intelligence (ICTAI 2017) 2017
System Description of Candy Kingdom - A Sweet Family of SAT Solvers Markus Iser, Felix Kutzner SAT COMPETITION 2017 2017
SAT Race 2015 Tomáš Balyo, Armin Biere, Markus Iser, Carsten Sinz Journal of Artificial Intelligence 2016
Beans and Eggs - Proteins for Glucose 3.0 Markus Iser SAT COMPETITION 2016 2016
Recognition of Nested Gates in CNF Formulas Markus Iser, Norbert Manthey, Carsten Sinz International Conference on Theory and Applications of Satisfiability Testing (SAT 2015) 2015
Minimizing Models for Tseitin-Encoded SAT Instances Markus Iser, Carsten Sinz, Mana Taghdiri International Conference on Theory and Applications of Satisfiability Testing (SAT 2013) 2013
Optimizing MiniSAT Variable Orderings for the Relational Model Finder Kodkod Markus Iser, Mana Taghdiri, Carsten Sinz International Conference on Theory and Applications of Satisfiability Testing (SAT 2012) 2012
MiniSAT 09z for SAT-Competition 2009 Markus Iser SAT 2009 competitive events booklet 2009
Problem-Sensitive Restart Heuristics for the DPLL Procedure Carsten Sinz, Markus Iser International Conference on Theory and Applications of Satisfiability Testing (SAT 2009) 2009

Supervised Theses

Title Student Date Type
Automated Tuning and Portfolio Selection for SAT Solvers Tobias Fuchs Mai 2023 Master Thesis
Product Configuration as a MaxSMT Problem Björn Ehrlinspiel Apr. 2023 Master Thesis (external)
Fuzzy Clause Weights Through Trail Sampling Achim Kriso Mar. 2023 Master Thesis
Construction of Binary Decision Diagrams Maxim Popov Nov. 2022 Master Thesis (external)
Predicting Hardness and Runtime of SAT Instances Sajjad Ahmad Nov. 2022 Master Thesis (external)
Feature Importance in SAT Instance Classification Elizaveta Danilova Aug. 2022 Bachelor Thesis
Decision Heuristics in a Constraint-based Product Configurator Matthias Gorenflo Jun. 2022 Master Thesis (external)
A Novel SAT Solver Architecture Thomas Barthel Jun. 2022 Master Thesis (external)
Cluster Analysis for SAT Instances Paul Ferdinand Heinen Feb. 2022 Bachelor Thesis
Asynchronous Clause Exchange for Malleable SAT Solving Malte Sönnichsen Feb. 2022 Master Thesis
Selecting SAT Instances to Evaluate Solvers Youheng Lü Jul. 2021 Bachelor Thesis
Massively Parallel Software Verification with Mallob and LLBMC Christian Solomon Feb. 2021 Bachelor Thesis
Integer Arithmetic in SAT-based Product Configuration Nik Böttger Jun. 2020 Master Thesis (external)
Explainable k-Portfolios of SAT-Solvers Luc Mercatoris Apr. 2021 Bachelor Thesis
Efficient Approximation of Implicated Literals Applied in SAT-based Product Configuration Johannes Werner Dec. 2020 Master Thesis (external)
Recognition of Constraints in CNF Formulas Robin Link Oct. 2020 Bachelor Thesis
Controlling Heuristics in CDCL SAT Solving with Adaptive Centrality Computations Norbert Blümle Jan. 2020 Master Thesis
Automated Analysis of Runtime Experiments in SAT Solving Benjamin-Philipp Roth Nov. 2019 Bachelor Thesis
Exploiting Gate Structure to Direct CDCL Search via Variable Selection and Approximation Felix Kutzner Jun. 2016 Diploma Thesis
Kodierungen zur Lösung von Ressourcen-abhängigen Terminplanungsproblemen mittels Integer Linear Programming Norbert Blümle Nov. 2015 Bachelor Thesis
SAT-based Solutions to the Resource-constrained Project Scheduling Problem Christian Ammann Nov. 2015 Bachelor Thesis
SAT-basierte Lösungsverfahren für das Discrete Tomography Problem: Eine vergleichende Untersuchung Rosina Kazokova Jan. 2015 Bachelor Thesis