Title
Nonempty intersection of longest paths in series-parallel graphs.
Abstract
In 1966 Gallai asked whether all longest paths in a connected graph have nonempty intersection. This is not true in general and various counterexamples have been found. However, the answer to Gallai's question is positive for several well-known classes of graphs, as for instance connected outerplanar graphs, connected split graphs, and 2-trees. A graph is series-parallel if it does not contain K 4 as a minor. Series-parallel graphs are also known as partial 2-trees, which are arbitrary subgraphs of 2-trees. We present two independent proofs that every connected series-parallel graph has a vertex that is common to all of its longest paths. Since 2-trees are maximal series-parallel graphs, and outerplanar graphs are also series-parallel, our result captures these two classes in one proof and strengthens them to a larger class of graphs. We also describe how one such vertex can be found in linear time.
Year
DOI
Venue
2017
10.1016/j.disc.2016.07.023
Discrete Mathematics
Field
DocType
Volume
Discrete mathematics,Modular decomposition,Combinatorics,Indifference graph,Clique-sum,Chordal graph,Cograph,Pathwidth,1-planar graph,Mathematics,Split graph
Journal
340
Issue
ISSN
Citations 
3
0012-365X
0
PageRank 
References 
Authors
0.34
0
7
Name
Order
Citations
PageRank
Guantao Chen110725.00
Julia Ehrenmüller272.67
Cristina G. Fernandes326029.98
Carl Georg Heise410.70
Songling Shan5209.16
Ping Yang600.68
Amy N. Yates700.34