Title
Twins in graphs
Abstract
A basic pigeonhole principle insures an existence of two objects of the same type if the number of objects is larger than the number of types. Can such a principle be extended to a more complex combinatorial structure? Here, we address such a question for graphs. We call two disjoint subsets A,B of vertices twins if they have the same cardinality and induce subgraphs of the same size. Let t(G) be the largest k such that G has twins on k vertices each. We provide the bounds on t(G) in terms of the number of edges and vertices using discrepancy results for induced subgraphs. In addition, we give conditions under which t(G)=|V(G)|/2 and show that if G is a forest then t(G)=|V(G)|/2-1.
Year
DOI
Venue
2014
10.1016/j.ejc.2014.01.007
Eur. J. Comb.
Keywords
Field
DocType
vertices twin,largest k,induced subgraphs,basic pigeonhole principle,complex combinatorial structure,discrepancy result
Discrete mathematics,Graph,Combinatorics,Disjoint sets,Vertex (geometry),Cardinality,Mathematics,Pigeonhole principle
Journal
Volume
ISSN
Citations 
39,
European J. Combin 39 (2014), 188--197
1
PageRank 
References 
Authors
0.37
13
3
Name
Order
Citations
PageRank
Maria Axenovich120933.90
Ryan Martin214414.43
torsten ueckerdt314126.26