Extremal hypergraphs and bounds for the Turan density of the 4-uniform K-5
2009 (English)In: Discrete Mathematics, ISSN 0012-365X, E-ISSN 1872-681X, Vol. 309, no 16, 5231-5234 p.Article in journal (Refereed) Published
In this paper we find, for n <= 16, the maximum number of edges in a 4-uniform hypergraph which does not have the complete 4-uniform hypergraph on five vertices, K-5(4), as a subgraph. Equivalently, we find all optimal (n, n-4, n-5) covering designs for n <= 16. Using these results we find a new upper bound for the Turin density of K-5(4). pi(K-5(4)) <= 1753/2380 = 0.73655.... Finally we make some notes on the structure of the extremal 4-graphs for this problem and the conjectured extremal family. (C) 2009 Published by Elsevier B.V.
Place, publisher, year, edition, pages
2009. Vol. 309, no 16, 5231-5234 p.
turan hypergraphs, covering designs, turan density
Research subject Mathematical Statistics
IdentifiersURN: urn:nbn:se:umu:diva-31693DOI: 10.1016/J.Disc.2009.03.035ISI: 000269476700028OAI: oai:DiVA.org:umu-31693DiVA: diva2:293870