Alexander Bork

profile
Email
alexander.bork at cs.rwth-aachen.de
Address
Room 4205
Ahornstraße 55
D-52074 Aachen
Phone
+49 241 80 21252

I have been a PhD student at the Software Modeling and Verification Group (MOVES) headed by Professor Joost-Pieter Katoen since April 2021. Additionally, I am a doctoral researcher within the Research Training Group UnRAVeL.

Research

We cannot avoid POMDPs (…) because the real world is one.

Stuart J. Russel, Peter Norvig
Artificial Intelligence – A Modern Approach (Fourth Edition), p.578

My research focus is on the verification of partially observable stochastic models, in particular the analysis of partially observable Markov decision processes (POMDPs). In contrast to classical stochastic models, in partially observable models a decision maker must base its decisions on the available information in a state and not the complete state itself. A special focus of my work is the development of approaches that can be used in practice to verify certain properties on partially observable models and to synthesise strategies for such properties.

I am also interested in general topics of probabilistic verification, in particular probabilistic model checking.
I am a developer of the probabilistic model checker Storm.

Thesis Projects

If you are interested in writing a Bachelor’s/Master’s thesis within my research area, don’t hesitate to contact me!

Finished Projects

  • Sven Büge, Implementing Goal-HSVI for POMDPs in the Probabilistic Model Checker Storm, Bachelor’s Thesis, 2024.
  • Umut Dural, Automatic Algorithm Selection for Probabilistic Model Checking using Machine Learning, Bachelor’s Thesis, 2023.
  • Gergana Tropcheva, Strategy Computation for a Markovian Disease Spread Model, Bachelor’s thesis, 2023.
  • Christina Gehnen, POMDP-based Execution Models for Probabilistic Programs with Partial Observability, Master’s thesis, 2022. (co-supervised with Tobias Winkler)

Peer Reviews

Journals

  • Logical Methods in Computer Science (lmcs) 2022/23 – Reviewer

Conferences

Teaching

I’m currently involved in the following teaching activities:

Past Semesters

Publications

2024
DOI fulltext PDF [bibtex]
@conference{LEBPRPS2024,
title = {Learning Explainable and Better Performing Representations of POMDP Strategies},
author = {Alexander Nikolai Bork and Debraj Chakraborty and Kush Grover and Jan Křetínský and Stefanie Mohr},
publisher = {Springer},
booktitle = {LNCS},
volume = {14571},
pages = {299-319},
type = {Conference Paper},
year = {2024},
doi = {10.1007/978-3-031-57249-4_15},
url = { https://publications.rwth-aachen.de/record/992671},
}×
[issue] 		Alexander Nikolai Bork, Debraj Chakraborty, Kush Grover, Jan Křetínský, Stefanie Mohr. Learning Explainable and Better Performing Representations of POMDP Strategies, 30. International Conference TACAS (TACAS 2024), Volume 14571 of LNCS, 299-319, Springer, 2024.
2023
DOI fulltext PDF [bibtex]
@conference{SESPSP2023,
title = {Search and Explore: Symbiotic Policy Synthesis in POMDPs},
author = {Roman Andriushchenko and Alexander Nikolai Bork and Milan Češka and Sebastian Junges and Joost-Pieter Katoen and Filip Macák},
publisher = {Springer},
booktitle = {LNCS},
volume = {13966},
pages = {113-135},
type = {Conference Paper},
year = {2023},
doi = {10.1007/978-3-031-37709-9_6},
url = { https://publications.rwth-aachen.de/record/968844},
}×
[issue] 		Roman Andriushchenko, Alexander Nikolai Bork, Milan Češka, Sebastian Junges, Joost-Pieter Katoen, Filip Macák. Search and Explore: Symbiotic Policy Synthesis in POMDPs, 35. International Conference on Computer-Aided Verification (CAV 2023), Volume 13966 of LNCS, 113-135, Springer, 2023.
2022
DOI fulltext PDF [bibtex]
@conference{UAETRP2022,
title = {Under-Approximating Expected Total Rewards in POMDPs},
author = {Alexander Nikolai Bork and Joost-Pieter Katoen and Tim Quatmann},
publisher = {Springer},
booktitle = {LNCS},
volume = {13244},
pages = {22-40},
type = {Conference Paper},
year = {2022},
doi = {10.1007/978-3-030-99527-0_2},
url = { https://publications.rwth-aachen.de/record/844526},
}×
[issue] 		Alexander Nikolai Bork, Joost-Pieter Katoen, Tim Quatmann. Under-Approximating Expected Total Rewards in POMDPs, 28. International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS 2022), Volume 13244 of LNCS, 22-40, Springer, 2022.
2021
[bibtex]
@masterthesis{UP2021,
title = {Underapproximations for indefinite-horizon POMDPS},
author = {Alexander Nikolai Bork},
institution = {RWTH Aachen University},
type = {Master Thesis},
year = {2021},
url = { https://publications.rwth-aachen.de/record/972076},
}×
[issue] 		Alexander Nikolai Bork. Underapproximations for indefinite-horizon POMDPS, Master Thesis, RWTH Aachen University, 2021.
2020
DOI [bibtex]
@conference{VIHP2020,
title = {Verification of Indefinite-Horizon POMDPs},
author = {Alexander Nikolai Bork and Sebastian Junges and Joost-Pieter Katoen and Tim Quatmann},
publisher = {Springer},
booktitle = {LNCS},
volume = {12302},
pages = {288-304},
type = {Conference Paper},
year = {2020},
doi = {10.1007/978-3-030-59152-6_16},
url = { https://publications.rwth-aachen.de/record/814779},
}×
[issue] 		Alexander Nikolai Bork, Sebastian Junges, Joost-Pieter Katoen, Tim Quatmann. Verification of Indefinite-Horizon POMDPs, International Symposium on Automated Technology for Verification and Analysis (ATVA 2020), Volume 12302 of LNCS, 288-304, Springer, 2020.