Clemens Thielen

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We consider the complexity of the traveling tournament problem, which is a well-known benchmark problem in tournament timetabling. The problem was supposed to be computationally hard ever since its proposal in 2001. Recently, the first NP-completeness proof has been given for the variant of the problem were no constraints on the number of consecutive home(More)
We consider a variant of the generalized assignment problem (GAP) where the amount of space used in each bin is restricted to be either zero (if the bin is not opened) or above a given lower bound (aminimum quantity). We provide several complexity results for different versions of the problem and give polynomial time exact algorithms and approximation(More)
We provide a general scheme for constructing monotone algorithms for a wide class C of scheduling problems Q|prec, rj |γ on related machines with precedence constraints and/or release dates. Our scheme works in the offline and the online setting. It takes as input two approximation/competitive algorithms for the (simpler) scheduling problems P |prec, rj |γ(More)