2011 LocalApproximabilityofMaxMinand

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Subject Headings: Max-Min Linear Program.

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Abstract

In a max-min LP, the objective is to maximise ω subject to A x1, C xω 1, and x0. In a min-max LP, the objective is to minimise ρ subject to A xρ 1, C x1, and x0. The matrices A and C are nonnegative and sparse: each row a i of A has at most ΔI positive elements, and each row c k of C has at most ΔK positive elements.

We study the approximability of max-min LPs and min-max LPs in a distributed setting; in particular, we focus on local algorithms (constant-time distributed algorithms). We show that for any ΔI ≥2, ΔK ≥2, and ε>0 there exists a local algorithm that achieves the approximation ratio ΔI (1−1/ΔK )+ε. We also show that this result is the best possible: no local algorithm can achieve the approximation ratio ΔI (1−1/ΔK ) for any ΔI ≥2 and ΔK ≥2.

1. Introduction

In a max-min linear program (max-min LP), the objective is to (1)

maximise [math]\displaystyle{ w }[/math]
subject to [math]\displaystyle{ A\bf{x} \le 1; C\bf{x} \ge \lt math\gt w }[/math] 1; \bf{x} \ge 0.</math>

A min-max linear program (min-max LP) is analogous: the objective is to (2)

minimise [math]\displaystyle{ p }[/math]
subject to [math]\displaystyle{ A\bf{x} \le p 1; C\bf{x} \ge 1; \bf{x} \ge 0. }[/math]

In both cases, A and C are nonnegative matrices.

In this work, we study max-min LPs and min-max LPs in a distributed setting. We present a local algorithm (constant-time distributed algorithm) for approximating these LPs, and we show that the approximation factor of our algorithm is the best possible among all local algorithms.

References

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 AuthorvolumeDate ValuetitletypejournaltitleUrldoinoteyear
2011 LocalApproximabilityofMaxMinandPetteri Kaski
Patrik Floréen
Marja Hassinen
Joel Kaasinen
Topi Musto
Jukka Suomela
Local Approximability of Max-Min and Min-Max Linear Programs10.1007/s00224-010-9303-6