Title
Stability and Turan Numbers of a Class of Hypergraphs via Lagrangians
Abstract
Given a family of r-uniform hypergraphs F (or r-graphs for brevity), the Turan number ex(n, F) of F is the maximum number of edges in an r-graph on n vertices that does not contain any member of F. A pair {u, v} is covered in a hypergraph G if some edge of G contains {u, v}. Given an rgraph F and a positive integer p >= n(F), where n(F) denotes the number of vertices in F, let H-p(F) denote the r-graph obtained as follows. Label the vertices of F as v1,..., v n(F). Add new vertices v(n(F)+1),..., vp. For each pair of vertices v(i), v(j) not covered in F, add a set B-i,(j) of r - 2 new vertices and the edge {v(i), v(j)}U B-i,B- j, where the B-i,B- j are pairwise disjoint over all such pairs {i, j}. We call H-p(F) the expanded p-clique with an embedded F. For a relatively large family of F, we show that for all sufficiently large n, ex(n, H-p(F)) = | T-r(n, p - 1)|, where T-r(n, p - 1) is the balanced complete (p - 1)-partite r-graph on n vertices. We also establish structural stability of near-extremal graphs. Our results generalize or strengthen several earlier results and provide a class of hypergraphs for which the Turan number is exactly determined (for large n).
Year
DOI
Venue
2017
10.1017/S0963548316000444
COMBINATORICS PROBABILITY & COMPUTING
Field
DocType
Volume
Integer,Discrete mathematics,Graph,Combinatorics,Disjoint sets,Vertex (geometry),Hypergraph,Constraint graph,Mathematics
Journal
26
Issue
ISSN
Citations 
3
0963-5483
3
PageRank 
References 
Authors
0.43
10
3
Name
Order
Citations
PageRank
axel brandt130.43
David E. Irwin289998.12
Tao Jiang3638.69