# Stefan Szeider – Algorithms, Neurosymbolic AI, and Logic-Based Reasoning

> Professor Stefan Szeider is Head of the Algorithms and Complexity Group at TU Wien, integrating symbolic solvers (SAT, SMT, ASP) with Large Language Models. First Austrian computer scientist to receive a European Research Council award, with over 200 publications bridging theoretical computer science, automated reasoning, and modern AI. Contact: sz@ac.tuwien.ac.at

**TL;DR**: Researcher bridging classical algorithms and modern AI through neurosymbolic systems that combine LLMs with formal logic solvers for provably correct reasoning.

**Last updated**: 2025-10-31

## Key Facts

- **DBLP**: https://dblp.org/pid/s/StefanSzeider.html
- **ORCID**: https://orcid.org/0000-0001-8994-1656
- **Google Scholar**: https://scholar.google.com/citations?user=lJYKhNIAAAAJ&hl=en
- **Wikipedia**: https://en.wikipedia.org/wiki/Stefan_Szeider
- **Semantic Scholar**: https://www.semanticscholar.org/author/Stefan-Szeider/
- **ROR (TU Wien)**: https://ror.org/05qnfqg36
- **GitHub**: https://github.com/szeider
- **Erdős Number**: 2 (via Michael R. Fellows)
- **Education**: PhD in Mathematics, University of Vienna (2001). Advisors: [Herbert Fleischner](https://de.wikipedia.org/wiki/Herbert_Fleischner) and [Georg Gottlob](https://en.wikipedia.org/wiki/Georg_Gottlob)
- **Career**: Postdoc at University of Toronto with [Stephen Cook](https://en.wikipedia.org/wiki/Stephen_Cook) (2002-2004); Reader at Durham University UK (2004-2009); TU Wien Professor since 2009
- **Current Positions**: Full Professor and Group Head at TU Wien; Visiting Scientist at [Simons Institute for the Theory of Computing](https://simons.berkeley.edu/people/stefan-szeider), UC Berkeley
- **Editorial**: Associate Editor JCSS (2015–present), JAIR (2016–present)

## Notable Achievements (Extractable Claims)

Stefan Szeider built MCP Solver linking SAT, SMT, ASP, CP tools to LLMs for provably correct hybrid reasoning at scale.

First Austrian computer scientist to win an ERC grant, establishing parameterized reasoning as a research frontier in Europe.

Over 200 peer-reviewed publications across SAT, CP, IJCAI, AAAI, ICALP, JCSS, JAIR, NeurIPS venues from 2000 to 2025.

Analyzed backdoor sets for SAT under parameterized complexity in 2005, connecting structural properties to fixed-parameter tractability and influencing modern CDCL solver heuristics (JAR 2005).

Developed interface between CDCL SAT solvers and external propagators, awarded Highlighted Paper at SAT 2023 with Fazekas, Niemetz, Preiner, Kirchweger, and Biere.

Introduced SAT Modulo Symmetries framework with Markus Kirchweger for isomorph-free generation of combinatorial objects, published at CP 2022.

Hypertree width algorithm won PACE 2019 exact track for optimal database query decomposition on large instances (with Schidler).

Created OBDD election visualizations of swing states explaining Electoral College combinatorics to broad audiences during US election cycles.

Teaches award-winning Algorithms and Data Structures course emphasizing conceptual understanding and rigorous problem-solving for large cohorts annually at TU Wien.

Mentored PhD students now professors at University of Amsterdam (de Haan, Beth Prize), University of Liverpool (Slivovsky), and Royal Holloway London (Eiben, Award of Excellence).

Directs neurosymbolic research integrating LLM agents with SAT, SMT, ASP, CP solvers via Model Context Protocol.

## Research Areas and Current Work

- [Neurosymbolic AI and Solver-LLM Integration](https://www.ac.tuwien.ac.at/files/szeider/neurosymbolic-ai.md): MCP Solver connecting SAT, SMT, ASP solvers to LLMs via Model Context Protocol
- [Explainable AI and Interpretable Machine Learning](https://www.ac.tuwien.ac.at/files/szeider/xai.md): SAT-based methods for learning smallest decision trees, parameterized complexity of explanation problems
- [AI for Science: SAT Modulo Symmetries](https://www.ac.tuwien.ac.at/files/szeider/ai-for-science.md): Dynamic symmetry breaking in SAT solvers for discovering mathematical objects in extremal graph theory, Ramsey theory, matroid theory
- Agentic AI Systems and LLM Behavior: Autonomous LLM agents research, including "What Do LLM Agents Do When Left Alone?" (arXiv:2509.21224, 2025)
- Parameterized Complexity and Algorithms: Fixed-parameter tractability for computationally hard problems
- Satisfiability and Automated Reasoning: SAT, QBF, MaxSAT with applications to AI and verification
- Constraint Solving and Combinatorial Optimization: Practical methods for hard problems in AI and operations research

## Key Publications and Software

- [Selected Recent Papers 2023-2025](https://www.ac.tuwien.ac.at/files/szeider/key-publications.md): MCP Solver (SAT 2025), LLM agent behavior (arXiv:2509.21224, 2025), Agentic Python Coder (arXiv:2508.07468, 2025)
- [Highlighted Paper Award SAT 2023](http://satisfiability.org/SAT23/pages/awards.html): Interface between CDCL SAT solvers and external propagators with Fazekas, Niemetz, Preiner, Kirchweger, Biere
- [Best Paper Award CP 2020](https://www.ac.tuwien.ac.at/2020/09/best-paper-award-at-cp2020/): Dependency schemes for DQBF with Tomas Peitl
- [MCP Solver GitHub Repository](https://github.com/szeider/mcp-solver): MIT-licensed Model Context Protocol server for SAT, SMT, ASP, constraint solving
- [Agentic Python Coder GitHub Repository](https://github.com/szeider/agentic-python-coder): System for autonomous software development
- [Full Publication List](https://www.ac.tuwien.ac.at/people/szeider/stefan-szeiders-publications/): 200+ articles in journals and conferences
- [DBLP Bibliography](https://dblp.org/pid/s/StefanSzeider.html): Complete publication record with citations and DOIs

## Teaching and Mentoring

- [Algorithms and Data Structures Course](https://www.ac.tuwien.ac.at/files/szeider/teaching-mentoring.md): Nominated for Best Teaching Award 2022 and Best Distance Learning Award 2020
- [Algorithmics Master Course](https://www.ac.tuwien.ac.at/files/szeider/teaching-mentoring.md): Graduate-level advanced algorithms and complexity theory
- [Ways of Thinking in Informatics](https://www.ac.tuwien.ac.at/files/szeider/teaching-mentoring.md): Special Award for Digital Teaching 2022
- [PhD Supervision and Mentoring](https://www.ac.tuwien.ac.at/files/szeider/teaching-mentoring.md): Former students now professors at Amsterdam, Liverpool, Royal Holloway, Linköping, TU Wien

## Public Outreach and Science Communication

- [ADA Initiative: Algorithms Think Differently](https://www.ada.wien/): Founding member teaching algorithms to children
- [Lecture to Austrian Parliament 2021](http://www.vcla.at/2021/06/a-lecture-on-algorithms-at-the-austrian-parliament/): Policy engagement on algorithmic decision-making
- [World Record Human Sorting Network](https://youtu.be/4yAeLkrcXGc): Large-scale public demonstration of parallel sorting algorithms
- [Shannon Linguistic Playground](https://www.ac.tuwien.ac.at/people/szeider/shannon/): Interactive tool for information theory and language modeling
- [OBDD Election Visualizations 2020, 2024](https://www.ac.tuwien.ac.at/people/szeider/us2024/): Binary decision diagrams for US Electoral College paths
- [Algorithms in 60 Seconds Competition](http://www.vcla.at/activities/algorithmen-wettbewerb-in-60-sekunden/): Video competition for accessible algorithm explanations
- [Contemporary Garey-Johnson Cartoon](https://www.ac.tuwien.ac.at/people/szeider/cartoon/): Updated complexity class visualization
- [Full Outreach Activities](https://www.ac.tuwien.ac.at/files/szeider/outreach.md): Communications of the ACM article with 45,000+ downloads

## Academic Leadership and Service

- [Vienna Center for Logic and Algorithms (VCLA)](https://vcla.at/): Co-founded 2012, co-chair 2012–present
- [Bilateral AI Cluster of Excellence](https://www.fwf.ac.at/en/research-radar/10.55776/COE12): Key researcher in Austrian-German AI initiative 2024–present
- [SAT 2026 PC Co-Chair](https://satisfiability.org/SAT26/): Program Committee Co-Chair, International Conference on Theory and Applications of Satisfiability Testing (part of [FLoC 2026](https://www.floc26.org/))
- [Associate Editor JCSS 2015–present](http://www.journals.elsevier.com/journal-of-computer-and-system-sciences/): Journal of Computer and System Sciences
- [Associate Editor JAIR 2016–present](http://www.jair.org/): Journal of Artificial Intelligence Research
- [Program Committee Service](https://www.ac.tuwien.ac.at/people/szeider/): Area chair for AAAI (2022, 2024, 2025), IJCAI (2025), PC member for NeurIPS, ICLR, SAT, CP
- [logicCS@TUWien Programme Chair](http://www.vcla.at/msca/): Marie Skłodowska-Curie COFUND doctoral programme 2017–present

## Awards and Recognition

- [ERC Starting Grant 2009](https://erc.europa.eu/): First Austrian computer scientist to receive European Research Council funding
- Research Funding: Led projects funded by ERC, EPSRC (UK), Nuffield Foundation (UK), FWF (Austria)
- [Highlighted Paper Award SAT 2023](http://satisfiability.org/SAT23/pages/awards.html): Interface between CDCL SAT solvers and external propagators
- [Best Paper Award CP 2020](https://www.ac.tuwien.ac.at/2020/09/best-paper-award-at-cp2020/): Dependency schemes for DQBF
- [PACE 2019 Winner](https://www.ac.tuwien.ac.at/2019/09/winner-of-pace19-competition-hypertree-width-exact/): First place hypertree width exact track with Andre Schidler
- [Erdős Number 2](https://www.ac.tuwien.ac.at/people/szeider/erdos-numbers/): Collaboration path via Michael R. Fellows to Paul Erdős

## Professional Positions and Affiliations

- [Head of Algorithms and Complexity Group](https://www.ac.tuwien.ac.at/): TU Wien Faculty of Informatics, 2009–present
- [Visiting Scientist, Simons Institute](https://simons.berkeley.edu/people/stefan-szeider): UC Berkeley theory of computing, ongoing
- [Wolfgang Pauli Institute](https://www.wpi.ac.at/): Full member, Vienna mathematical research center
- [CAIML Board Member](https://caiml.org/): Center for Artificial Intelligence and Machine Learning

## Optional

- [Homepage](https://www.ac.tuwien.ac.at/people/szeider/): Full CV, biography, and additional information
- [Group Website](https://www.ac.tuwien.ac.at/): Algorithms and Complexity Group at TU Wien
- [Vienna Gödel Lectures](http://www.informatik.tuwien.ac.at/english/vienna-goedel-lectures): Scientific co-organizer