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JOURNAL OF
ALGEBRAIC
COMBINATORICS

  Editors-in-chief: C. A. Athanasiadis, T. Lam, A. Munemasa, H. Van Maldeghem
ISSN 0925-9899 (print) • ISSN 1572-9192 (electronic)
 

Minimal half-spaces and external representation of tropical polyhedra

Stéphane Gaubert and Ricardo D. Katz

DOI: 10.1007/s10801-010-0246-4

Abstract

We give a characterization of the minimal tropical half-spaces containing a given tropical polyhedron, from which we derive a counter-example showing that the number of such minimal half-spaces can be infinite, contradicting some statements which appeared in the tropical literature, and disproving a conjecture of F. Block and J. Yu. We also establish an analogue of the Minkowski-Weyl theorem, showing that a tropical polyhedron can be equivalently represented internally (in terms of extreme points and rays) or externally (in terms of half-spaces containing it). A canonical external representation of a polyhedron turns out to be provided by the extreme elements of its tropical polar. We characterize these extreme elements, showing in particular that they are determined by support vectors.

Pages: 325–348

Keywords: keywords max-plus semiring; max-plus convexity; tropical convexity; polyhedra; polytopes; Minkowski-Weyl theorem; supporting half-spaces

Full Text: PDF

References

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