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Laboratoire de théorie du calcul 2

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Publications associées (155)

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Anchor View Allocation for Collaborative Free Viewpoint Video Streaming

Pascal Frossard

In free viewpoint video, a viewer can choose at will any camera angle or the so-called "virtual view" to observe a dynamic 3-D scene, enhancing his/her depth perception. The virtual view is synthesized using texture and depth videos of two anchor camera vi ...

2015

No Small Linear Program Approximates Vertex Cover within a Factor 2 - e

Ola Nils Anders Svensson, Abbas Bazzi

The vertex cover problem is one of the most important and intensively studied combinatorial optimization problems. Khot and Regevproved that the problem is NP-hard to approximate within a factor2 - ∈, assuming the Unique Games Conjecture (UGC). This is tig ...

IEEE Computer Society2015

Strong LP formulations for scheduling splittable jobs on unrelated machines

Ola Nils Anders Svensson

A natural extension of the makespan minimization problem on unrelated machines is to allow jobs to be partially processed by different machines while incurring an arbitrary setup time. In this paper we present increasingly stronger LP-relaxations for this ...

Springer Heidelberg2015

Improving Christofides' Algorithm for the s-t Path TSP

Hyung Chan An

We present a deterministic (1+root 5/2)-approximation algorithm for the s-t path TSP for an arbitrary metric. Given a symmetric metric cost on n vertices including two prespecified endpoints, the problem is to find a shortest Hamiltonian path between the t ...

Assoc Computing Machinery2015

Approximating ATSP by Relaxing Connectivity

Ola Nils Anders Svensson

The standard LP relaxation of the asymmetric traveling salesman problem has been conjectured to have a constant integrality gap in the metric case. We prove this conjecture when restricted to shortest path metrics of node-weighted digraphs. Our arguments a ...

IEEE Computer Society2015

Maximizing Symmetric Submodular Functions

Moran Feldman

Symmetric submodular functions are an important family of submodular functions capturing many interesting cases including cut functions of graphs and hypergraphs. In this work, we identify submodular maximization problems for which one can get a better app ...

Springer Int Publishing Ag2015

On the configuration LP for maximum budgeted allocation

Ola Nils Anders Svensson, Christos Kalaitzis, Lukas Polacek, Aleksander Madry

We study the maximum budgeted allocation problem, i.e., the problem of selling a set of m indivisible goods to n players, each with a separate budget, such that we maximize the collected revenue. Since the natural assignment LP is known to have an integral ...

Springer Heidelberg2015

Sparse Group Covers and Greedy Tree Approximations

Volkan Cevher, Luca Baldassarre

We consider the problem of finding a K-sparse approximation of a signal, such that the support of the approximation is the union of sets from a given collection, a.k.a. group structure. This problem subsumes the one of finding K-sparse tree approximations. ...

2015

Towards Tight Lower Bounds for Scheduling Problems

Ashkan Norouzi Fard, Abbas Bazzi

We show a close connection between structural hardness for k-partite graphs and tight inapproximability results for scheduling problems with precedence constraints. Assuming a natural but nontrivial generalisation of the bipartite structural hardness resul ...

Springer Int Publishing Ag2015

A Tight Linear Time (1/2)-Approximation For Unconstrained Submodular Maximization

Moran Feldman

We consider the Unconstrained Submodular Maximization problem in which we are given a nonnegative submodular function f : 2(N) -> R+, and the objective is to find a subset S subset of N maximizing f(S). This is one of the most basic submodular optimization ...

Siam Publications2015