Fachbereich Mathematik

AG Optimierung

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Prof. Dr. Stefan Ruzika

Anschrift

Paul-Ehrlich-Straße
Gebäude 14 , Raum 457
67663 Kaiserslautern

Postfach 3049
67653 Kaiserslautern

Kontakt

Tel.: +49 631 205 4423
Fax: +49 631 205 4737
E-Mail: ruzika@mathematik.uni-kl.de

Prof. Dr. Stefan Ruzika

Aktuelle Vorlesungen

Im Wintersemester 2022/23 biete ich folgende Vorlesungen und Veranstaltungen an:

Grundlagen der Mathematik II für Studierende des Lehramts

Integer Programming: Polyhedral Theory and Algorithms

Reading Course

Proseminar Big Data Analysis

Proseminar Modellierung in der Wirtschaftsmathematik

Forschungsinteressen

  • Multikriterielle Optimierung
  • Ganzzahlige und kombinatorische Optimierung
  • Mathematische Modellierung
  • Optimierungsprobleme auf Netzwerken
  • Approximationsalgorithmen

Forschungsprojekte

Ich arbeite zur Zeit an folgenden Forschungsprojekten:

Ageing Smart

General Approximation Methods for Multicriteria Optimization Problems

MAL-i

SchuMaMoMINT

Veröffentlichungen

  • On the hardness of covering-interdiction problems
    N. Fröhlich, S. Ruzika,
    Theoretical Computer Science 871, pp. 1-15 (2021)

  • A Reduced-Complexity Projection Algorithm for ADMM-based LP Decoding
    F. Gensheimer, T. Dietz, K. Kraft, S. Ruzika, N. Wehn,
    IEEE Transactions on Information Theory (2020)

  • The binary knapsack problem with qualitative levels
    L. E. Schäfer, T. Dietz, M. Barbati, J. Figueira, S. Greco, S. Ruzika,
    European Journal of Operational Research (2020)

  • An approximation algorithm for a general class of parametric optimization problems
    C. Bazgan, A. Herzel, S. Ruzika, C. Thielen, D. Vanderpooten,
    Journal of Combinatorial Optimization, pp. 1-31 (2020)

  • One-exact approximate Pareto sets
    A. Herzel, C. Bazgan, S. Ruzika, C. Thielen, D. Vanderpooten,
    Journal of Global Optimization, pp. 1-29 (2020)

  • On the rectangular knapsack problem: approximation of a specific quadratic knapsack problem
    B. Schulze, M. Stiglmayr, L. Paquete, C. M. Fonseca, D. Willems, S. Ruzika,
    Mathematical Methods of Operations Research, pp. 1-26 (2020)

  • An inner approximation method to compute the weight set decomposition of a triobjective mixed-integer problem
    P. Halffmann, T. Dietz, A. Przybylski, S. Ruzika,
    Journal of Global Optimization (2020)

  • Sparsifying parity-check matrices
    L. Russo, T. Dietz, J. Figueira, A. P. Francisco, S. Ruzika,
    Applied Soft Computing 96, pp. 106601 (2020)

  • Maximising the clustering coefficient of networks and the effects on habitat network robustness
    H. Heer, L. Streib, R. B. Schäfer, S. Ruzika,
    Plos one 15, pp. e0240940 (2020)

  • Shortest paths with ordinal weights
    L. E. Schäfer, T. Dietz, N. Fröhlich, S. Ruzika, J. R. Figueira,
    European Journal of Operational Research 280, pp. 1160-1170 (2020)

  • On the p-hub interdiction problem
    T. Ullmert, S. Ruzika, A. Schöbel,
    Computers & Operations Research 124, pp. 105056 (2020)

  • How does habitat connectivity influence the colonization success of a hemimetabolous aquatic insect? - A modeling approach
    L. Streib, M. Kattwinkel, H. Heer, S. Ruzika, R. B. Schäfer,
    Ecological Modelling 416, pp. 108909 (2020)

  • Introducing multiobjective complex systems
    T. Dietz, K. Klamroth, K. Kraus, S. Ruzika, L. E. Schäfer, B. Schulze, M. Stiglmayr, M. M. Wiecek,
    European Journal of Operational Research 280, pp. 581-596 (2020)

  • Unified Education: Medienbildung entlang der Lehrerbildungskette-Maßnahmen im Rahmen der Qualitätsoffensive Lehrerbildung der TU Kaiserslautern
    M. Bracke, C. Gomez-Tutor, J. Kuhn, S. Ruzika,
    Mitteilungen der Gesellschaft für Didaktik der Mathematik 45, pp. 33-38 (2019)

  • Optimisation Model of Dispersal Simulations on a Dendritic Habitat Network
    H. Heer, L. Streib, M. Kattwinkel, R. B. Schäfer, S. Ruzika,
    Scientific Reports 9, pp. 1-11 (2019)

  • Approximation Schemes For the Parametric Knapsack Problem
    A. Giudici, P. Halffmann, S. Ruzika, C. Thielen,
    Information Processing Letters 120, pp. 11-15 (2017)

  • A General Approximation Method for Bicriteria Minimization Problems
    P. Halffmann, S. Ruzika, C. Thielen, D. Willems,
    Theoretical Computer Science 695, pp. 1-15 (2017)

  • Multiobjective optimization for interwoven systems
    K. Klamroth, S. Mostaghim, B. Naujoks, S. Poles, R. Purshouse, G. Rudolph, S. Ruzika, S. Sayin, M. M. Wiecek, X. Yao,
    Journal of Multi-Criteria Decision Analysis 24, pp. 71-81 (2017)

  • A coverage-based Box-Algorithm to compute a representation for optimization problems with three objective functions
    T. Kuhn, S. Ruzika,
    Journal of Global Optimization 67, pp. 581-600 (2017)

  • Shortest Paths with Shortest Detours
    C. Torchiani, J. Ohst, D. Willems, S. Ruzika,
    Journal of Optimization Theory and Applications 174, pp. 858-874 (2017)

  • Easy to say they are Hard, but Hard to see they are Easy - Towards a Categorization of Tractable Multiobjective Combinatorial Optimization Problems
    J. Figueira, C. M. Fonseca, P. Halffmann, K. Klamroth, L. Paquete, S. Ruzika, B. Schulze, M. Stiglmayr, D. Willems,
    Journal of Multi-Criteria Decision Analysis 24, pp. 82-98 (2017)

  • A hybrid and multiscale approach to model and simulate mobility in the context of public events
    D. H. Biedermann, C. Torchiani, P. M. Kielar, D. Willems, O. Handel, S. Ruzika, A. Borrmann,
    Transportation Research Procedia 19, pp. 350-363 (2016)

  • Evacuation modeling: a case study on linear and nonlinear network flow models
    S. Göttlich, S. Kühn, J. Ohst, S. Ruzika,
    EURO journal on computational optimization 4, pp. 219-239 (2016)

  • Hypervolume subset selection in two dimensions: Formulations and algorithms
    T. Kuhn, C. M. Fonseca, L. Paquete, S. Ruzika, M. M. Duarte, J. Figueira,
    Evolutionary Computation 24, pp. 411-425 (2016)

  • Fahrgastwechselzeiten von Shuttlebussen
    C. Torchiani, M. J. Seitz, D. Willems, S. Ruzika, G. Köster,
    H. TUM-I1517. TU München: Universität Koblenz-Landau 2015 (2015)

  • Comments on: Static and dynamic source locations in undirected networks
    S. Ruzika, C. Torchiani,
    TOP 23, pp. 655-659 (2015)

  • Multiple objective branch and bound for mixed 0-1 linear programming: Corrections and improvements for the biobjective case
    T. Vincent, F. Seipp, S. Ruzika, A. Przybylski, X. Gandibleux,
    Computers & Operations Research 40, pp. 498-509 (2013)

  • Bidirectional coupling of macroscopic and microscopic pedestrian evacuation models
    A. Borrmann, A. Kneidl, G. Köster, S. Ruzika, M. Thiemann,
    Safety science 50, pp. 1695-1703 (2012)

  • Generalized multiple objective bottleneck problems
    J. Gorski, K. Klamroth, S. Ruzika,
    Operations Research Letters 40, pp. 276-281 (2012)

  • Mathematical programming decoding of binary linear codes: Theory and algorithms
    M. Helmling, S. Ruzika, A. Tanatmis,
    IEEE Transactions on Information Theory 58, pp. 4753-4769 (2012)

  • Committee selection under weight constraints
    C. Klamler, U. Pferschy, S. Ruzika,
    Mathematical Social Sciences 64, pp. 48-56 (2012)

  • Min-Max quickest path problems
    S. Ruzika, M. Thiemann,
    Networks 60, pp. 253-258 (2012)

  • Evacuation dynamics influenced by spreading hazardous material
    S. Göttlich, S. Kühn, J. Ohst, S. Ruzika, M. Thiemann,
    Networks & Heterogeneous Media 6, pp. 443-464 (2011)

  • Connectedness of efficient solutions in multiple objective combinatorial optimization
    J. Gorski, K. Klamroth, S. Ruzika,
    Journal of Optimization Theory and Applications 150, pp. 475-497 (2011)

  • Earliest arrival flows on series-parallel graphs
    S. Ruzika, H. Sperber, M. Steiner,
    Networks 57, pp. 169-173 (2011)

  • On k-max-optimization
    J. Gorski, S. Ruzika,
    Operations Research Letters 37, pp. 23-26 (2009)

  • Improved epsilon-constraint method for multiobjective programming
    M. Ehrgott, S. Ruzika,
    Journal of Optimization Theory and Applications 138, pp. 375 (2008)

  • Finding representative systems for discrete bicriterion optimization problems
    H. W. Hamacher, C. Pedersen, S. Ruzika,
    Operations Research Letters 35, pp. 336-344 (2007)

  • Multiple objective minimum cost flow problems: A review
    H. W. Hamacher, C. Pedersen, S. Ruzika,
    European Journal of Operational Research 176, pp. 1404-1422 (2007)

  • An Exact Algorithm for Solving Weight-Constrained Combinatorial Optimization Problems
    S. Ruzika,
    Electronic Notes in Discrete Mathematics, pp. 143-144 (2006)

  • Algorithms for time-dependent bicriteria shortest path problems
    H. W. Hamacher, S. Ruzika, S. A. Tjandra,
    Discrete optimization 3, pp. 238-254 (2006)

  • Approximation methods in multiobjective programming
    S. Ruzika, M. M. Wiecek,
    Journal of optimization theory and applications 126, pp. 473-501 (2005)

  • Detecting local convexity on the Pareto surface
    G. Fadel, Y. Li, S. Konda, M. M. Wiecek, S. Ruzika,
    Journal of Multi-Criteria Decision Analysis 11, pp. 45-54 (2002)

  • Multikriterielle Optimierung und Entscheidungsunterstützung: Tagungsband GOR Entscheidungstheorie und-praxis 2018
    K. Küfer, S. Ruzika, P. Halffmann,
    Springer-Verlag, (2019)

  • On Variants of the Single-criterion and Multiobjective Near-Shortest Paths Problem
    L. E. Schäfer, S. Ruzika,
    Multikriterielle Optimierung und Entscheidungsunterstützung, Springer Fachmedien Wiesbaden, pp. 17-30 (2019)

  • Wie man einen Testsieger kürt
    S. Ruzika, V. Klöckner, S. Gecks,
    Digitale Werkzeuge, Simulationen und mathematisches Modellieren, Springer, pp. 229-252 (2018)

  • On a Technique for Finding Running Tracks of Specific Length in a Road Network
    D. Willems, O. Zehner, S. Ruzika,
    Operations Research Proceedings 2017, Springer, pp. 333-338 (2018)

  • Evakuierungsszenarien in Modellierungswochen - ein interessantes und spannendes Thema für den Mathematikunterricht
    S. Ruzika, H. Siller, M. Bracke,
    Neue Materialien für einen realitätsbezogenen Mathematikunterricht 3, Springer, pp. 181-190 (2017)

  • Evakuierungsszenarien in Modellierungswochen-ein interessantes und spannendes Thema für den Mathematikunterricht
    S. Ruzika, H. Siller, M. Bracke,
    Neue Materialien für einen realitätsbezogenen Mathematikunterricht 3, Springer, pp. 181-190 (2017)

  • Influence of Spreading Hazardous Material in Macroscopic Evacuation Dynamics: A Proof of Concept
    S. Göttlich, S. Kühn, J. Ohst, S. Ruzika,
    Pedestrian and Evacuation Dynamics 2012, Springer, pp. 275-282 (2014)

  • A sandwich approach for evacuation time bounds
    H. W. Hamacher, S. Heller, W. Klein, G. Köster, S. Ruzika,
    Pedestrian and Evacuation Dynamics, Springer, pp. 503-513 (2011)

  • Quickest cluster flow problems
    H. W. Hamacher, K. Leiner, S. Ruzika,
    Pedestrian and Evacuation Dynamics, Springer, pp. 327-336 (2011)

  • Bidirectional coupling of macroscopic and microscopic approaches for pedestrian behavior prediction
    A. Kneidl, M. Thiemann, A. Borrmann, S. Ruzika, H. W. Hamacher, G. Köster, E. Rank,
    Pedestrian and Evacuation Dynamics, Springer, pp. 459-470 (2011)

  • Quickest cluster flow problems on tree networks
    K. Leiner, S. Ruzika,
    Network Optimization, Springer, pp. 243-255 (2011)

  • Reliable and restricted quickest path problems
    S. Ruzika, M. Thiemann,
    Network Optimization, Springer, pp. 309-314 (2011)

  • Flach spielen, hoch gewinnen: Fußball und Wissenschaft
    H. W. Hamacher, S. Ruzika,
    Shaker, (2010)

  • A survey on multiple objective minimum spanning tree problems
    S. Ruzika, H. W. Hamacher,
    Algorithmics of Large and Complex Networks, Springer, pp. 104-116 (2009)

  • On multiple objective combinatorial optimization
    S. Ruzika,
    Verlag Dr. Hut, (2007)

  • Kosten oder Reisezeit? Bikriterielle Optimierung der integrierten Fahr- und Umlaufplanung
    P. Schiewe, A. Schöbel, S. Ruzika,
    Preprint Heureka'21 (2020)

  • The Bicriterion Maximum Flow Network Interdiction Problem in s-t-Planar Graphs
    L. E. Schäfer, T. Dietz, M. V. Natale, S. Ruzika, S. O. Krumke, C. M. Fonseca,
    Operations Research Proceedings 2019, pp. 133-139 (2020)

  • An FPTAS for a General Class of Parametric Optimization Problems
    C. Bazgan, A. Herzel, S. Ruzika, C. Thielen, D. Vanderpooten,
    International Computing and Combinatorics Conference, pp. 25-37 (2019)

  • On the role of multicriteria decision support in mathematical modelling
    S. Ruzika, L. Schneider,
    Eleventh Congress of the European Society for Research in Mathematics Education 24 (2019)

  • A Low-Complexity Projection Algorithm for ADMM-Based LP Decoding
    F. Gensheimer, T. Dietz, S. Ruzika, K. Kraft, N. Wehn,
    2018 IEEE 10th International Symposium on Turbo Codes & Iterative Information Processing (ISTC), pp. 1-5 (2018)

  • Improved Maximum-Likelihood Decoding Using Sparse Parity-Check Matrices
    F. Gensheimer, T. Dietz, S. Ruzika, K. Kraft, N. Wehn,
    2018 25th International Conference on Telecommunications (ICT), pp. 236-240 (2018)

  • ADMM versus simplex algorithm for LP decoding
    F. Gensheimer, S. Ruzika, S. Scholl, N. Wehn,
    9th International Symposium on Turbo Codes and Iterative Information Processing (ISTC), 2016, pp. 211-215 (2016)

  • A hybrid and multiscale approach to model and simulate mobility in the context of public events
    D. H. Biedermann, C. Torchiani, P. M. Kielar, D. Willems, O. Handel, S. Ruzika, A. Borrmann,
    Transportation Research Procedia (19), pp. 350-363 (2016)

  • A simplex algorithm for LP decoding hardware
    F. Gensheimer, S. Ruzika, S. Scholl, N. Wehn,
    Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014 IEEE 25th Annual International Symposium on, pp. 790-794 (2014)

  • Efficient maximum-likelihood decoding of linear block codes on binary memoryless channels
    M. Helmling, E. Rosnes, S. Ruzika, S. Scholl,
    Information Theory (ISIT), 2014 IEEE International Symposium on, pp. 2589-2593 (2014)

  • Towards combinatorial LP turbo decoding
    M. Helmling, S. Ruzika,
    2013 IEEE International Symposium on Information Theory Proceedings (ISIT), pp. 1491-1495 (2013)

  • Integer programming as a tool for analysis of channel codes
    S. Scholl, F. Kienle, M. Helmling, S. Ruzika,
    Systems, Communication and Coding (SCC), Proceedings of 2013 9th International ITG Conference on, pp. 1-6 (2013)

  • ML vs. BP decoding of binary and non-binary LDPC codes
    S. Scholl, F. Kienle, M. Helmling, S. Ruzika,
    Turbo Codes and Iterative Information Processing (ISTC), 2012 7th International Symposium on, pp. 71-75 (2012)

  • Mathematical modeling of earthwork optimization problems
    Y. Ji, F. Seipp, A. Borrmann, S. Ruzika, E. Rank,
    Proc. of the International Conference on Computing in Civil and Building Engineering (ICCCBE) (2010)

  • Calculating the minimum distance of linear block codes via integer programming
    M. Punekar, F. Kienle, N. Wehn, A. Tanatmis, S. Ruzika, H. W. Hamacher,
    Turbo Codes and Iterative Information Processing (ISTC), 2010 6th International Symposium on, pp. 329-333 (2010)

  • A Lagrangian relaxation based decoding algorithm for LTE turbo codes
    A. Tanatmis, S. Ruzika, F. Kienle,
    Turbo Codes and Iterative Information Processing (ISTC), 2010 6th International Symposium on, pp. 369-373 (2010)

  • Numerical comparison of IP formulations as ML decoders
    A. Tanatmis, S. Ruzika, M. Punekar, F. Kienle,
    Communications (ICC), 2010 IEEE International Conference on, pp. 1-5 (2010)

  • Committee selection with a weight constraint based on lexicographic rankings of individuals
    C. Klamler, U. Pferschy, S. Ruzika,
    International Conference on Algorithmic DecisionTheory, pp. 50-61 (2009)

  • Valid inequalities for binary linear codes
    A. Tanatmis, S. Ruzika, H. W. Hamacher, M. Punekar, F. Kienle, N. Wehn,
    IEEE International Symposium on Information Theory, 2009. ISIT 2009., pp. 2216-2220 (2009)

  • A separation algorithm for improved LP-decoding of linear block codes
    A. Tanatmis, S. Ruzika, H. W. Hamacher, M. Punekar, F. Kienle, N. Wehn,
    5th International Symposium on Turbo Codes and Related Topics, 2008, pp. 37-42 (2008)

  • Hub location's tool box: Integer programming, heuristics, aggregation, multiobjective optimization
    S. Baumgartner, E. O. Gavriliouk, H. W. Hamacher, T. Meyer, S. Ruzika,
    Extended Abstract, ISOLDE X Meeting, Sevilla, Spain (2005)

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