Zilverling

dr. M. Walter (Matthias)

Assistant Professor
EEMCS-AM-MOR
Zilverling 4005
m.walter@utwente.nl
+31534898744
Business card

I obtained my PhD at Otto-von-Guericke University Magdeburg. I work on solving techniques for mixed-integer programs (MIPs) on the practical side (branch-and-cut, branch-and-price) as well as polyhedral combinatorics on the theoretical side.

Expertise

  • Computer Science

    • Algorithms
    • System Analysis
    • Integer Programming
    • Linear Programming
    • Classes
    • Complexity

  • Mathematics

    • Polytope
    • Integer

Organisations

Publications

2026

A hybrid solution approach for the Integrated Healthcare Timetabling Competition 2024 (2026)Operations Research, Data Analytics and Logistics. Guericke, D., van der Hulst, R., Karimpour, A., Schrader, I. & Walter, M.https://doi.org/10.1016/j.ordal.2026.200502Network submatrices in mixed-integer optimization (2026)[Thesis › PhD Thesis - Research UT, graduation UT]. University of Twente. van der Hulst, R.https://doi.org/10.3990/1.9789036571531

2025

Geometry of the Reformulation-Linearization-Technique: Domination of Disjunctions (2025)[Working paper › Preprint]. ArXiv.org. Hof, H. A. & Walter, M.https://doi.org/10.48550/arXiv.2511.13805A hybrid solution approach for the Integrated Healthcare Timetabling Competition 2024 (2025)[Working paper › Preprint]. ArXiv.org. Guericke, D., van der Hulst, R., Karimpour, A., Schrader, I. & Walter, M.https://doi.org/10.48550/arXiv.2511.04685A Row-wise Algorithm for Graph Realization (2025)[Working paper › Preprint]. ArXiv.org. van der Hulst, R. & Walter, M.https://doi.org/10.48550/arXiv.2408.12869Implied Integrality in Mixed-Integer Optimization (2025)In Integer Programming and Combinatorial Optimization: 26th International Conference, IPCO 2025, Proceedings (pp. 452-465) (Lecture Notes in Computer Science; Vol. 15620). Springer. van der Hulst, R. & Walter, M.https://doi.org/10.1007/978-3-031-93112-3_33Improved linear programming relaxations for flow shop problems with makespan minimization (2025)Computers & operations research, 177. Article 106970. Wallrath, R., Franke, M. & Walter, M.https://doi.org/10.1016/j.cor.2024.106970scipopt/papilo: v2.4.2 (2025)[Dataset Types › Dataset]. Zenodo. Hoen, A., Gottwald, L., Schlösser, F., Vigerske, S., Manns, J., Palacios, G. K., Walter, M., Gleixner, A., Besançon, M., James, J., Jabs, C., Mexi, G., Prouvost, A., Ghannam, M. & Bolusani, S.https://doi.org/10.5281/zenodo.6414881scipopt/soplex: v7.1.4 (2025)[Dataset Types › Dataset]. Zenodo. Miltenberger, M., Gleixner, A., Eifler, L., Koch, T., Hoen, A., Vigerske, S., Schlösser, F., Nicolas-Thouvenin, J., Rehfeldt, D., Hendel, G., Besançon, M., Manns, J., Steffy, D., Mexi, G., Pfetsch, M., James, J., Gottwald, L., Walter, M. & Ebrahim, A.https://doi.org/10.5281/zenodo.6414885Implied Integrality in Mixed-Integer Optimization (2025)[Working paper › Preprint]. ArXiv.org. van der Hulst, R. & Walter, M.https://doi.org/10.48550/arXiv.2504.07209

Research profiles

Current projects

Combinatorial Matrix Recognition

Software Library

A set of tools for recognizing certain combinatorial matrices, such as totally unimodular, balanced, network or series-parallel matrices.

Investigating Polyhedra by Oracles

Software Library

Investigating Polyhedra by Oracles (IPO) is a C++ library that enables the analysis of polyhedra that are given implicitly by means of an optimization oracle. The main application is the search for inequalities that are facet-defining for the mixed-integer hull of some mixed-integer optimization problem.

Making Mixed-Integer Programming Solvers Smarter and Faster using Network Matrices

Mixed-integer optimization is a technique to solve complex optimization problems which arise in production planning, logistics and routing. This research will improve the solver software to make it faster. To achieve this, algorithms to find well-known patterns in a given formulation will be developed and tested.

Address

University of Twente

Zilverling (building no. 11), room 4005
Hallenweg 19
7522 NH Enschede
Netherlands

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