Extremal hypergraphs and bounds for the Turán density of the 4-uniform K5
نویسنده
چکیده
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,K4 5 , 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 Turán density ofK4 5 . π(K4 5 ) ≤ 1753 2380 = 0.73655 . . . . Finally wemake some notes on the structure of the extremal 4-graphs for this problem and the conjectured extremal family. © 2009 Published by Elsevier B.V.
منابع مشابه
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ورودعنوان ژورنال:
- Discrete Mathematics
دوره 309 شماره
صفحات -
تاریخ انتشار 2009