Title
Quadruple systems with independent neighborhoods
Abstract
A 4-graph is odd if its vertex set can be partitioned into two sets so that every edge intersects both parts in an odd number of points. Letb(n)=maxα{α(n−α3)+(n−α)(α3)}=(12+o(1))(n4) denote the maximum number of edges in an n-vertex odd 4-graph. Let n be sufficiently large, and let G be an n-vertex 4-graph such that for every triple xyz of vertices, the neighborhood N(xyz)={w:wxyz∈G} is independent. We prove that the number of edges of G is at most b(n). Equality holds only if G is odd with the maximum number of edges. We also prove that there is ε>0 such that if the 4-graph G has minimum degree at least (1/2−ε)(n3), then G is 2-colorable.
Year
DOI
Venue
2008
10.1016/j.jcta.2008.01.008
Journal of Combinatorial Theory, Series A
Keywords
Field
DocType
k-Graph,Turán problem,Independent neighborhoods
Discrete mathematics,Graph,Combinatorics,Monad (category theory),Vertex (geometry),Parity (mathematics),Conjecture,Mathematics
Journal
Volume
Issue
ISSN
115
8
0097-3165
Citations 
PageRank 
References 
8
0.65
4
Authors
3
Name
Order
Citations
PageRank
Zoltan Füredi1312.75
Dhruv Mubayi257973.95
Oleg Pikhurko331847.03