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An approximation algorithm for a general class of multi-parametric optimization problems

Helfrich, S.; Herzel, A.; Ruzika, S.; Thielen, C. (2022)

Journal of Combinatorial Optimization 44.
DOI: 10.1007/s10878-022-00902-w


Open Access
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An approximation algorithm for a general class of parametric optimization problems

Bazgan, C.; Herzel, A.; Ruzika, S.; Thielen, C.; Vanderpooten, D. (2022)

Journal of Combinatorial Optimization 43 (5), S. 1328-1358.
DOI: 10.1007/s10878-020-00646-5


Open Access
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The power of the weighted sum secularization for approximating multiobjective optimization problems

Bazgan, C.; Ruzika, S.; Thielen, C.; Vanderpooten, D. (2022)

Theory of Computing Systems 66 (1), S. 395–415.
DOI: 10.1007/s00224-021-10066-5


Open Access
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Enforcing fuel-optimal traffic patterns

Boesen, S.; Raith, A.; Thielen, C.; Tidswell, J. (2021)

EURO Journal on Transportation and Logistics 2021 (10), S. 100060.
DOI: 10.1016/j.ejtl.2021.100060

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The Power of the Weighted Sum Scalarization for Approximating Multiobjective Optimization Problems

Bazgan, C.; Ruzika, S.; Thielen, C.; Vanderpooten, D. (2021)

Theory of Computing Systems 66 (2022), S. 395-415.
DOI: 10.1007/s00224-021-10066-5


Open Access
 

We determine the power of the weighted sum scalarization with respect to the computation of approximations for general multiobjective minimization and maximization problems. Additionally, we introduce a new multi-factor notion of approximation that is specifically tailored to the multiobjective case and its inherent trade-offs between different objectives. For minimization problems, we provide an efficient algorithm that computes an approximation of a multiobjective problem by using an exact or approximate algorithm for its weighted sum scalarization. In case that an exact algorithm for the weighted sum scalarization is used, this algorithm comes arbitrarily close to the best approximation quality that is obtainable by supported solutions – both with respect to the common notion of approximation and with respect to the new multi-factor notion. Moreover, the algorithm yields the currently best approximation results for several well-known multiobjective minimization problems. For maximization problems, however, we show that a polynomial approximation guarantee can, in general, not be obtained in more than one of the objective functions simultaneously by supported solutions.

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Proteinanalyse in NMR-Spektren mittels moderner Optimierungsverfahren

Krumpel, A.; Thielen, C. (2021)

Fachsymposium „Artificial Intelligence for Life“, Hochschule Weihenstephan-Triesdorf, Online (Zoom).


Minimising emissions in traffic assignment with non-monotonic arc costs

Tidswell, J.; Downward, A.; Thielen, C.; Raith, A. (2021)

Transportation Research Part B: Methodological 153, S. 70-90.
DOI: 10.1016/j.trb.2021.08.007

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An analysis of the stability of hinterland container transport cooperation, Transportation Science

Giudici, A.; Lu, T.; Thielen, C.; Zuidwijk, R. (2021)

Transportation Science (online first) 55 (5), S. 1170-1186.
DOI: 10.1287/trsc.2021.1050

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A (B+1)-approximation for network flow interdiction with unit costs, Discrete Applied Mathematics

Boeckmann, J.; Thielen, C. (2021)

Discrete Applied Mathematics (online first) 2021 (304).
DOI: 10.1016/j.dam.2021.07.008


Open Access
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Approximating the product knapsack problem

Pferschy, U.; Schauer, J.; Thielen, C. (2021)

Optimization Letters (Online first) 15 (6), S. 2529-2540.
DOI: 10.1007/s11590-021-01760-x


Open Access
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Approximation methods for multiobjective optimization problems: A survey

Herzel, A.; Ruzika, S.; Thielen, C. (2021)

INFORMS Journal on Computing 33 (4), S. 1284-1299.
DOI: 10.1287/ijoc.2020.1028


Open Access
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Mixed integer programming for dynamic tower crane and storage area optimization on construction sites

Riga, K.; Jahr, K.; Thielen, C.; Borrmann, A. (2020)

Automation in Construction 120, 103259.
DOI: 10.1016/j.autcon.2020.103259

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One-exact approximate Pareto sets

Herzel, A.; Bazgan, C.; Ruzika, S.; Thielen, C.; Vanderpooten, D. (2020)

Journal of Global Optimization 80, S. 87-115.
DOI: 10.1007/s10898-020-00951-7


Open Access
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Who witnesses The Witness? Finding witnesses in The Witness is hard and sometimes impossible

Abel, Z.; Bosboom, J.; Coulombe, M.; Demaine, E.; Hamilton, L.; Hesterberg, A....

Theoretical Computer Science 839, S. 41-102.
DOI: 10.1016/j.tcs.2020.05.031

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An approximation algorithm for a general class of parametric optimization problems

Bazgan, C.; Herzel, A.; Ruzika, S.; Thielen, C.; Vanderpooten, D. (2020)

Journal of Combinatorial Optimization 2020.
DOI: 10.1007/s10878-020-00646-5


Open Access
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An approximation algorithm for network flow interdiction with unit costs and two capacities

Boeckmann, J.; Thielen, C. (2020)

Graphs and Combinatorial Optimization: from Theory to Applications (CTW2020 Proceedings) 5, S. 157-169.
DOI: 10.1007/978-3-030-63072-0_13

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An FPTAS for a General Class of Parametric Optimization Problems

Bazgan, C.; Herzel, A.; Ruzika, S.; Thielen, C.; Vanderpooten, D. (2019)

Konferenzbeitrag für Proceedings of the 25th International Computing and Combinatorics Conference (COCOON) 11653, S. 25-37.
DOI: 10.1007/978-3-030-26176-4_3

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Sending a reliable cost-efficient flow through a stochastic timevarying network

Giudici, A.; Lu, T.; Thielen, C.; Zuidwijk, R. (2019)

Proceedings of the 10th Triennial Symposium on Transportation Analysis (TRISTAN) 2019, S. 1-4.


Full Implementation of social choice functions in dominant strategies

Krumke, S.; Thielen, C.; Weinschenk, P.; Westphal, S. (2018)

International Journal of Game Theory 48, S. 337-361.
DOI: 10.1007/s00182-018-0654-6

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Duty rostering for physicians at a department of orthopedics and trauma surgery

Thielen, C. (2018)

Operations Research for Health Care 19, S. 80-91.
DOI: 10.1016/j.orhc.2018.03.004

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Prof. Dr. Clemens Thielen


Hochschule Weihenstephan-Triesdorf

Fakultät Wald und Forstwirtschaft
Hans-Carl-von-Carlowitz-Platz 3
85354 Freising

T +49 9421 187-175
clemens.thielen[at]hswt.de