Coloring all directed paths in a symmetr
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Luisa Gargano; Pavol Hell; Stephane Perennes
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Article
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2001
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John Wiley and Sons
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English
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## Abstract Let __T__ be a symmetric directed tree, i.e., an undirected tree with each edge viewed as two opposite arcs. We prove that the minimum number of colors needed to color the set of all directed paths in __T__, so that two paths of the same color never use the same directed arc of __T__, i