Research
We study, develop, and apply formal methods to software systems, with a strong emphasis on tools that automate formal verification. Our foundational research spans concurrency theory, model checking, probabilistic computation, program analysis, and formal semantics.
Research highlights
Storm
A symbolic and explicit-state probabilistic model checker with a modular architecture and a Python interface. Storm supports models including dynamic fault trees and stochastic Petri nets.
Caesar
A deductive verifier for randomised algorithms, implemented in Rust. Its quantitative intermediate verification language and SMT backends support prototyping and combining verification techniques.
Prophesy
A tool supporting scalable parameter synthesis for probabilistic models. Our techniques have automatically synthesised the optimal randomisation bias in Herman’s ring protocol, a self-stabilising distributed algorithm.
COMPASS
A comprehensive toolset for extended AADL, developed with FBK Trento and support from the European Space Agency. COMPASS applies probabilistic model checking in aerospace and has been validated on industrial case studies.
C-program verification and NITWIT
We have developed software model checking for C programs in automation and verified key automotive software components. NITWIT independently checks violation witnesses produced by software model checkers.
Attestor
Automated verification of Java programs operating on dynamic data structures. Attestor checks shape and correctness properties, supports procedure-modular reasoning, and gives visual feedback when properties are violated.
Reasoning about probabilistic programs
We develop weakest precondition calculi for expected runtime analysis and exact inference in probabilistic programs. Extensions of separation logic support proofs about randomised algorithms manipulating dynamic data structures.
Earlier projects
- FRAPPANT – Formal Reasoning About Probabilistic Programs: Breaking New Ground for Automation
- APPA – Automated Probabilistic Program Analysis
- CAP Sino-German Project
- CARP: Correct and Efficient Accelerator Programming
- CATSY: Catalogue of System and Software Properties
- D-MILS: Distributed MILS for Dependable Information and Communication Infrastructures
- HODRIAN: Highly-Robust, Wireless Communication Components for Industrial Applications
- Juggrnaut: Verifying Pointer Programs with Unbounded Heap Structures
- Research Training Group UnRAVeL
- SENSATION: Self Energy-Supporting Autonomous Computation
- Testing for AADL
- VPLC: Verification of Programmable Logic Controller Code
Publications
2026
- Conference paper
Scalable Verification of Neural Control Barrier Functions Using Linear Bound Propagation
Annual Learning for Dynamics and Control Conference, 17-19 June 2026, Los Angeles, California, USA
- Conference paper
Generating Functions Meet Occupation Measures: Invariant Synthesis for Probabilistic Loops
Programming languages and systems
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Probabilistic programming meets automata theory: Exact inference using weighted automata
Theoretical computer science
- Conference paper
Fast Computation of Conditional Probabilities in MDPs and Markov Chain Families
Computer Aided Verification
- Journal article
Search and explore: symbiotic policy synthesis in POMDPs
Formal methods in system design
- Conference paper
Tools and Algorithms for Sound Multi-Objective Probabilistic Model Checking
Formal Methods
- Conference paper
Correction to: Weighted Automata for Exact Inference in Discrete Probabilistic Programs
Theoretical Aspects of Computing – ICTAC 2025
- Conference paper
Highly Incremental: A Simple Programmatic Approach for Many Objectives
Formal Methods
- Patent
Verfahren zur Herstellung flächiger, poröser Hydrogele mittels Fluss-Lithographie
- Journal article
The revised practitioner’s guide to MDP model checking algorithms
International journal on software tools for technology transfer
- Preprint
Highly Incremental: A Simple Programmatic Approach for Many Objectives (Extended Version)
PDF of Highly Incremental: A Simple Programmatic Approach for Many Objectives (Extended Version)RWTH record for Highly Incremental: A Simple Programmatic Approach for Many Objectives (Extended Version)BibTeX for Highly Incremental: A Simple Programmatic Approach for Many Objectives (Extended Version) - Conference paper
Generalized Parameter Lifting: Finer Abstractions for Parametric Markov Chains
Automated technology for verification and analysis
- Conference paper
Weighted Automata for Exact Inference in Discrete Probabilistic Programs
Theoretical Aspects of Computing – ICTAC 2025
- Conference paper
Facing Uncertainty in AI: From Formal Verification To Synthesis
Theoretical Aspects of Computing – ICTAC 2025
- Book chapter
The Optimal Strategy to Meet the Deadline: Ask Christel!
Principles of formal quantitative analysis
- Artifact
Zenodo
2025
- Journal article
ACM SIGLOG news
- Conference paper
CertPHash: Towards Certified Perceptual Hashing via Robust Training
Proceedings of the 34th USENIX Security Symposium
- Conference paper
Quantifier Elimination and Craig Interpolation: The Quantitative Way
Foundations of Software Science and Computation Structures