TY - GEN A1 - Grötschel, Martin A1 - Raack, Christian A1 - Werner, Axel T1 - Towards optimizing the deployment of optical access networks N2 - 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. T3 - ZIB-Report - 13-11 KW - FTTx, FTTH, FTTB, FTTC, FTTN, telecommunications, access networks, passive optical networks, network design, routing, energy efficiency Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-18627 SN - 1438-0064 ER - TY - GEN A1 - Raack, Christian A1 - Raymond, Annie A1 - Werner, Axel A1 - Schlechte, Thomas T1 - Integer Programming and Sports Rankings N2 - 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. T3 - ZIB-Report - 13-19 KW - sport ranking KW - integer programming Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-18068 SN - 1438-0064 ER - TY - JOUR A1 - Raack, Christian A1 - Raymond, Annie A1 - Schlechte, Thomas A1 - Werner, Axel T1 - Standings in sports competitions using integer programming JF - Journal of Quantitative Analysis in Sports Y1 - 2013 U6 - https://doi.org/10.1515/jqas-2013-0111 VL - 10 IS - 2 SP - 131 EP - 137 PB - De Gruyter ER - TY - JOUR A1 - Grötschel, Martin A1 - Raack, Christian A1 - Werner, Axel T1 - Towards optimizing the deployment of optical access networks JF - EURO Journal on Computational Optimization Y1 - 2013 U6 - https://doi.org/10.1007/s13675-013-0016-x VL - 2 SP - 17 EP - 53 PB - Springer ER - TY - JOUR A1 - Betker, Andreas A1 - Kosiankowski, Dirk A1 - Lange, Christoph A1 - Pfeuffer, Frank A1 - Raack, Christian A1 - Werner, Axel ED - Helber, Stefan ED - Breitner, Michael ED - Rösch, Daniel ED - Schön, Cornelia ED - Graf von der Schulenburg, Johann-Matthias ED - Sibbertsen, Philipp ED - Steinbach, Marc ED - Weber, Stefan ED - Wolter, Anja T1 - Energy efficiency in extensive IP-over-WDM networks with protection JF - Operations Research Proceedings 2012 Y1 - 2014 U6 - https://doi.org/10.1007/978-3-319-00795-3_14 SP - 93 EP - 99 PB - Springer ER - TY - JOUR A1 - Leitner, Markus A1 - Ljubić, Ivana A1 - Sinnl, Markus A1 - Werner, Axel T1 - On the Two-Architecture Connected Facility Location Problem JF - Electronic Notes in Discrete Mathematics Y1 - 2013 U6 - https://doi.org//10.1016/j.endm.2013.05.113 VL - 41 SP - 359 EP - 366 CY - Costa Adeje ER - TY - JOUR A1 - Werner, Axel T1 - Kombinatorische Optimierung und die 40-Punkte-Regel JF - Mitteilungen der DMV Y1 - 2011 VL - 19 SP - 153 EP - 157 ER - TY - JOUR A1 - Werner, Axel A1 - Wotzlaw, Ronald T1 - On linkages in polytope graphs JF - Adv. Geom. Y1 - 2011 U6 - https://doi.org/10.1515/ADVGEOM.2011.015 VL - 11 IS - 3 SP - 411 EP - 427 ER - TY - GEN A1 - Uslu, Svenja A1 - Werner, Axel T1 - A Two-Phase Method for the Biobjective k-Architecture Connected Facility Location Problem and Hypervolume Computation N2 - 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. T3 - ZIB-Report - 15-08 KW - Biobjective Optimization KW - Connected Facility Location KW - Hypervolume Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-53753 SN - 1438-0064 ER - TY - JOUR A1 - Paffenholz, Andreas A1 - Werner, Axel T1 - Constructions for 4-polytopes and the cone of flag vectors. JF - Contemporary Mathematics Y1 - 2006 VL - 423 SP - 283 EP - 303 PB - Algebraic and geometric combinatorics. Euroconference in mathematics, algebraic and geometric combinatorics, Anogia, Crete, Greece, August 20–26, 2005. Providence, RI: American Mathematical Society (AMS) ER -