@misc{GroetschelRaackWerner2013, author = {Gr{\"o}tschel, Martin and Raack, Christian and Werner, Axel}, title = {Towards optimizing the deployment of optical access networks}, issn = {1438-0064}, doi = {10.1007/s13675-013-0016-x}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-18627}, year = {2013}, abstract = {In this paper we study the cost-optimal deployment of optical access networks considering variants of the problem such as fiber to the home (FTTH), fiber to the building (FTTB), fiber to the curb (FTTC), or fiber to the neighborhood (FTTN). We identify the combinatorial structures of the most important sub-problems arising in this area and model these, e.g., as capacitated facility location, concentrator location, or Steiner tree problems. We discuss modeling alternatives as well. We finally construct a "unified" integer programming model that combines all sub-models and provides a global view of all these FTTx problems. We also summarize computational studies of various special cases.}, language = {en} } @misc{RaackRaymondWerneretal.2013, author = {Raack, Christian and Raymond, Annie and Werner, Axel and Schlechte, Thomas}, title = {Integer Programming and Sports Rankings}, issn = {1438-0064}, doi = {10.1515/jqas-2013-0111}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-18068}, year = {2013}, abstract = {Sports rankings are obtained by applying a system of rules to evaluate the performance of the participants in a competition. We consider rankings that result from assigning an ordinal rank to each competitor according to their performance. We develop an integer programming model for rankings that allows us to calculate the number of points needed to guarantee a team the ith position, as well as the minimum number of points that could yield the ith place. The model is very general and can thus be applied to many types of sports. We discuss examples coming from football (soccer), ice hockey, and Formula~1. We answer various questions and debunk a few myths along the way. Are 40 points enough to avoid relegation in the Bundesliga? Do 95 points guarantee the participation of a team in the NHL playoffs? Moreover, in the season restructuration currently under consideration in the NHL, will it be easier or harder to access the playoffs? Is it possible to win the Formula~1 World Championship without winning at least one race or without even climbing once on the podium? Finally, we observe that the optimal solutions of the aforementioned model are associated to extreme situations which are unlikely to happen. Thus, to get closer to realistic scenarios, we enhance the model by adding some constraints inferred from the results of the previous years.}, language = {en} } @article{RaackRaymondSchlechteetal.2013, author = {Raack, Christian and Raymond, Annie and Schlechte, Thomas and Werner, Axel}, title = {Standings in sports competitions using integer programming}, volume = {10}, journal = {Journal of Quantitative Analysis in Sports}, number = {2}, publisher = {De Gruyter}, doi = {10.1515/jqas-2013-0111}, pages = {131 -- 137}, year = {2013}, language = {en} } @article{GroetschelRaackWerner2013, author = {Gr{\"o}tschel, Martin and Raack, Christian and Werner, Axel}, title = {Towards optimizing the deployment of optical access networks}, volume = {2}, journal = {EURO Journal on Computational Optimization}, publisher = {Springer}, doi = {10.1007/s13675-013-0016-x}, pages = {17 -- 53}, year = {2013}, language = {en} } @article{BetkerKosiankowskiLangeetal.2014, author = {Betker, Andreas and Kosiankowski, Dirk and Lange, Christoph and Pfeuffer, Frank and Raack, Christian and Werner, Axel}, title = {Energy efficiency in extensive IP-over-WDM networks with protection}, journal = {Operations Research Proceedings 2012}, editor = {Helber, Stefan and Breitner, Michael and R{\"o}sch, Daniel and Sch{\"o}n, Cornelia and Graf von der Schulenburg, Johann-Matthias and Sibbertsen, Philipp and Steinbach, Marc and Weber, Stefan and Wolter, Anja}, publisher = {Springer}, doi = {10.1007/978-3-319-00795-3_14}, pages = {93 -- 99}, year = {2014}, language = {en} } @article{LeitnerLjubićSinnletal.2013, author = {Leitner, Markus and Ljubić, Ivana and Sinnl, Markus and Werner, Axel}, title = {On the Two-Architecture Connected Facility Location Problem}, volume = {41}, journal = {Electronic Notes in Discrete Mathematics}, address = {Costa Adeje}, doi = {/10.1016/j.endm.2013.05.113}, pages = {359 -- 366}, year = {2013}, language = {en} } @article{Werner2011, author = {Werner, Axel}, title = {Kombinatorische Optimierung und die 40-Punkte-Regel}, volume = {19}, journal = {Mitteilungen der DMV}, pages = {153 -- 157}, year = {2011}, language = {en} } @article{WernerWotzlaw2011, author = {Werner, Axel and Wotzlaw, Ronald}, title = {On linkages in polytope graphs}, volume = {11}, journal = {Adv. Geom.}, number = {3}, doi = {10.1515/ADVGEOM.2011.015}, pages = {411 -- 427}, year = {2011}, language = {en} } @misc{UsluWerner2015, author = {Uslu, Svenja and Werner, Axel}, title = {A Two-Phase Method for the Biobjective k-Architecture Connected Facility Location Problem and Hypervolume Computation}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-53753}, year = {2015}, abstract = {We apply customized versions of the ε-constraint Method and the Two-Phase Method to a problem originating in access network planning. We introduce various notions of quality measures for approximated/partial sets of nondominated points, utilizing the concept of hypervolume for biobjective problems. We report on computations to assess the performance of the two methods in terms of these measures.}, language = {en} } @article{PaffenholzWerner2006, author = {Paffenholz, Andreas and Werner, Axel}, title = {Constructions for 4-polytopes and the cone of flag vectors.}, volume = {423}, journal = {Contemporary Mathematics}, publisher = {Algebraic and geometric combinatorics. Euroconference in mathematics, algebraic and geometric combinatorics, Anogia, Crete, Greece, August 20-26, 2005. Providence, RI: American Mathematical Society (AMS)}, pages = {283 -- 303}, year = {2006}, language = {en} }