Title
Rooted directed path graphs are leaf powers
Abstract
Leaf powers are a graph class which has been introduced to model the problem of reconstructing phylogenetic trees. A graph G=(V,E) is called k-leaf power if it admits a k-leaf root, i.e., a tree T with leaves V such that uv is an edge in G if and only if the distance between u and v in T is at most k. Moroever, a graph is simply called leaf power if it is a k-leaf power for some k@?N. This paper characterizes leaf powers in terms of their relation to several other known graph classes. It also addresses the problem of deciding whether a given graph is a k-leaf power. We show that the class of leaf powers coincides with fixed tolerance NeST graphs, a well-known graph class with absolutely different motivations. After this, we provide the largest currently known proper subclass of leaf powers, i.e, the class of rooted directed path graphs. Subsequently, we study the leaf rank problem, the algorithmic challenge of determining the minimum k for which a given graph is a k-leaf power. Firstly, we give a lower bound on the leaf rank of a graph in terms of the complexity of its separators. Secondly, we use this measure to show that the leaf rank is unbounded on both the class of ptolemaic and the class of unit interval graphs. Finally, we provide efficient algorithms to compute 2|V|-leaf roots for given ptolemaic or (unit) interval graphs G=(V,E).
Year
DOI
Venue
2010
10.1016/j.disc.2009.10.006
Discrete Mathematics
Keywords
Field
DocType
fixed tolerance nest graphs,interval graphs,rooted directed path graphs,leaf powers,strongly chordal graphs,ptolemaic graphs,leaf roots,graph class inclusions,(unit) interval graphs,interval graph,lower bound,phylogenetic tree
Discrete mathematics,Block graph,Comparability graph,Combinatorics,Indifference graph,Line graph,Graph power,Distance-hereditary graph,Symmetric graph,Pathwidth,Mathematics
Journal
Volume
Issue
ISSN
310
4
Discrete Mathematics
Citations 
PageRank 
References 
7
0.68
23
Authors
4
Name
Order
Citations
PageRank
Andreas Brandstädt11306129.88
Christian Hundt2836.34
Federico Mancini3789.79
Peter Wagner470.68