Trees with depression three
نویسندگان
چکیده
منابع مشابه
Hybridization Number on Three Trees
Phylogenetic networks are leaf-labelled directed acyclic graphs that are used to describe nontreelike evolutionary histories and are thus a generalization of phylogenetic trees. The hybridization number of a phylogenetic network is the sum of all indegrees minus the number of nodes plus one. The Hybridization Number problem takes as input a collection of phylogenetic trees and asks to construct...
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We prove that every tree of order n 5 with three leaves is (n + 1)-unavoidable. More precisely, we prove that every tree A with three leaves of order n is contained in every tournament T of order n + 1 except if (T ; A) is (R 5 ; S + 3) or its dual, where R 5 is the regular tournament on ve vertices and S + 3 is the outstar of degree three, that is, the tree consisting of a root dominating thre...
متن کاملA construction of a class of graphs with depression three
An edge ordering of a graph G is an injection f : E → R, the set of real numbers. A path in G for which the edge ordering f increases along its edge sequence is called an f -ascent ; an f -ascent is maximal if it is not contained in a longer f -ascent. The depression of G is the smallest integer k such that any edge ordering f has a maximal f -ascent of length at most k. We provide a constructi...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2008
ISSN: 0012-365X
DOI: 10.1016/j.disc.2007.07.039