Title
Upper bounds on the size of 4- and 6-cycle-free subgraphs of the hypercube
Abstract
In this paper we modify slightly Razborov's flag algebra machinery to be suitable for the hypercube. We use this modified method to show that the maximum number of edges of a 4-cycle-free subgraph of the n-dimensional hypercube is at most 0.6068 times the number of its edges. We also improve the upper bound on the number of edges for 6-cycle-free subgraphs of the n-dimensional hypercube from 2-1 to 0.3755 times the number of its edges. Additionally, we show that if the n-dimensional hypercube is considered as a poset then the maximum vertex density of three middle layers in an induced subgraph without 4-cycles is at most 2.15121(n@?n/2@?).
Year
DOI
Venue
2014
10.1016/j.ejc.2013.06.003
Eur. J. Comb.
Keywords
Field
DocType
modified method,induced subgraph,middle layer,flag algebra machinery,maximum vertex density,n-dimensional hypercube,4-cycle-free subgraph,6-cycle-free subgraphs,maximum number,upper bound
Discrete mathematics,Combinatorics,Vertex (geometry),Hypercube graph,Upper and lower bounds,Induced subgraph,Hypercube,Partially ordered set,Mathematics
Journal
Volume
ISSN
Citations 
35,
0195-6698
12
PageRank 
References 
Authors
0.80
16
4
Name
Order
Citations
PageRank
József Balogh186289.91
Ping Hu2324.05
Bernard Lidický318123.68
Hong Liu4398.54