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Characterization of the Distance between Subtrees of a Tree by the Associated Tight Span
Hiroshi Hirai
Research Institute for Mathematical Sciences, Kyoto University, Kyoto 606-8502, Japan
Annals of Combinatorics 10 (1) p.111-128 March, 2006
AMS Subject Classification: 52B05
A characterization is given to the distance between subtrees of a tree defined as the shortest path length between subtrees. This is a generalization of the four-point condition for tree metrics. For this, we use the theory of the tight span and obtain an extension of the famous result by Dress that a metric is a tree metric if and only if its tight span is a tree.
Keywords: tight span, tree metrics, the four-point condition


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