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We investigate the diameter of a natural abstraction of the 1-skeleton of polyhedra. Although this abstraction is simpler than other abstractions that were previously studied in the literature, the best upper bounds on the diameter of polyhedra continue to hold here. On the other hand, we show that this abstraction has its limits by providing a superlinear… (More)

We derive a new upper bound on the diameter of the graph of a polyhedron P = {x ∈ R<sup>n</sup> : Ax ≤ b}, where A ∈ Z<sup>m×n</sup>. The bound is polynomial in n and the largest absolute value of a sub-determinant of A, denoted by Δ. More precisely, we show that the diameter of P is bounded by O(Δ<sup>2</sup> n<sup>4</sup>… (More)

We consider a real-time scheduling problem that occurs in the design of software-based aircraft control. The goal is to distribute tasks τ i = (c i , p i) on a minimum number of identical machines and to compute offsets a i for the tasks such that no collision occurs. A task τ i releases a job of running time c i at each time a i + k · p i , k ∈ N 0 and a… (More)

We provide the currently fastest randomized (1+epsilon)-approximation algorithm for the closest lattice vector problem in the infinity-norm. The running time of our method depends on the dimension n and the approximation guarantee epsilon by 2<sup>(O(n))</sup> (log(1/epsilon))<sup>(O(n))</sup> which improves upon the (2+1/epsilon)<sup>(O(n))</sup> running… (More)

We study the simplex method over polyhedra satisfying certain " discrete curvature " lower bounds, which enforce that the boundary always meets vertices at sharp angles. Motivated by linear programs with totally unimodular constraint matrices, recent results of Bonifas et al (SOCG 2012), Brunsch and Röglin (ICALP 2013), and Eisenbrand and Vempala (2014)… (More)

The parametric lattice-point counting problem is as follows: Given an integer matrix A ∈ Z m×n , compute an explicit formula parameterized by b ∈ R m that determines the number of integer points in the polyhedron {x ∈ R n : Ax b}. In the last decade, this counting problem has received considerable attention in the literature. Several variants of Barvinok's… (More)

Kim defined a very general combinatorial abstraction of the diameter of polytopes called subset partition graphs to study how certain combinatorial properties of such graphs may be achieved in lower bound constructions. Using Lovász' Local Lemma, we give a general randomized construction for subset partition graphs satisfying strong adjacency and end-point… (More)

- K Hess Bellwald, F Eisenbrand, S Baruah, N Megow, Prof O N A Svensson, N Thèse +22 others
- 2012

If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is. Acknowledgements First and foremost I would like to express my deepest gratitude to my advisor Prof. Dr. Friedrich Eisenbrand. With his excellent lectures on linear and combinatorial optimization in Paderborn he sparked my interest in this… (More)