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Goossens D.,PostDoc Researcher for Research Foundation Flanders | Spieksma F.C.R.,Naamsestraat 69 | Leuven K.U.,Center for Operations Research and Business Statistics
IEEE SSCI 2011 - Symposium Series on Computational Intelligence - CISched 2011: 2011 IEEE Symposium on Computational Intelligence in Scheduling | Year: 2011

In sports scheduling, a team is said to have a break when it plays two home (or two away) matches in consecutive rounds. In this paper, we generalize this concept by also considering pairs of nonconsecutive rounds. We determine the complexity of the problem of finding a set of home-away patterns minimizing the number of generalized breaks when a so-called break set is given. Although the decision version of this problem can be solved in polynomial time, the optimization version turns out to be NP-hard. We also provide a lower bound for the number of generalized breaks for a given break set, and generalize a classic result by De Werra. We illustrate the relevance of generalized breaks with practical applications from, amongst others, the Belgian football league. © 2011 IEEE.


Goossens D.R.,Center for Operations Research and Business Statistics | Goossens D.R.,Catholic University of Leuven | Spieksma F.C.R.,Center for Operations Research and Business Statistics | Spieksma F.C.R.,Catholic University of Leuven
Operations Research Letters | Year: 2011

We generalize the concept of a break by considering pairs of arbitrary rounds. We show that a set of home-away patterns minimizing the number of generalized breaks cannot be found in polynomial time, unless P=NP. When all teams have the same break set, the decision version becomes easy; optimizing remains NP-hard. © 2011 Elsevier B.V. All rights reserved.


Goossens D.R.,Center for Operations Research and Business Statistics | Onderstal S.,University of Amsterdam | Spieksma F.C.R.,Center for Operations Research and Business Statistics
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering | Year: 2012

On May 7, 2011, over one hundred bidders took part in a combinatorial auction for housing space in a newly erected building in Amsterdam (the Netherlands). This paper describes the development of this auction. We sketch our collaboration with the housing corporation that resulted in design choices with respect to first/second price, feedback, number of rounds, and tractability of the combinatorial auction. Furthermore, the winner determination problem is complicated by various municipal and building regulations that the allocation needs to satisfy. We show how these regulations can be included in an integer program that is used to solve the winner determination problem. Finally, computational experiments illustrate the tractability of this model. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.


Goossens D.R.,Center for Operations Research and Business Statistics | Spieksma F.C.R.,Center for Operations Research and Business Statistics
Journal of Scheduling | Year: 2012

In this paper, we give an overview of the competition formats and the schedules used in 25 European soccer competitions for the season 2008-2009. We discuss how competitions decide the league champion, qualification for European tournaments, and relegation. Following Griggs and Rosa (Bull. ICA 18:65-68, 1996), we examine the popularity of the so-called canonical schedule. We investigate the presence of a number of properties related to successive home or successive away matches (breaks) and of symmetry between the various parts of the competition. We introduce the concept of ranking-balancedness, which is particularly useful to decide whether a fair ranking can be made.We also determine how the schedules manage the carry-over effect. We conclude by observing that there is quite some diversity in European soccer schedules, and that current schedules leave room for further optimizing. © Springer Science+Business Media, LLC 2011.

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