Cover-Decomposition and Polychromatic Numbers
Cover-Decomposition and Polychromatic Numbers
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DOI:
10.1007/978-3-642-23719-5_67
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发表时间:
2010-09
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影响因子:
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通讯作者:
B. Bollobás;David Pritchard;T. Rothvoss;A. Scott
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文献类型:
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作者:
B. Bollobás;David Pritchard;T. Rothvoss;A. Scott
A coloring of a hypergraph's vertices ispolychromaticif every hyperedge contains at least one vertex of each color; thepolychromatic numberis the maximum number of colors in such a coloring. Its dual, thecover-decomposition number, is the maximum number of disjoint hyperedge-covers. In geometric hypergraphs, there is extensive work on lower-bounding these numbers in terms of their trivial upper bounds (minimum hyperedge size and degree); our goal here is to broaden the study beyond geometric settings. We obtain algorithms yielding near-tight bounds for three families of hypergraphs: bounded hyperedge size, paths in trees, and bounded Vapnik--Chervonenkis (VC)-dimension. This reveals that discrepancy theory and iterated linear program relaxation are useful for cover-decomposition. Finally, we discuss the generalization of cover-decomposition to sensor cover.