Two Questions of Erdos on Hypergraphs above the Turan Threshold

被引:0
|
作者
Markstrom, Klas [1 ]
机构
[1] Umea Univ, Dept Math & Math Stat, S-90187 Umea, Sweden
关键词
turan problem; hypergraphs;
D O I
10.1002/jgt.21752
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
For ordinary graphs it is known that any graph G with more edges than the Turan number of Ks must contain several copies of Ks, and a copy of Ks+1-, the complete graph on s+1 vertices with one missing edge. Erdos asked if the same result is true for Ks3, the complete 3-uniform hypergraph on s vertices. In this note, we show that for small values of n, the number of vertices in G, the answer is negative for s=4. For the second property, that of containing a Ks+13-, we show that for s=4 the answer is negative for all large n as well, by proving that the Turan density of K53- is greater than that of K43.
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页码:101 / 105
页数:5
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