Two questions of Erd\H{o}s on hypergraphs above the Tur{\'a}n threshold}
Combinatorics
2011-11-28 v1 Discrete Mathematics
Abstract
For ordinary graphs it is known that any graph with more edges than the Tur{\'a}n number of must contain several copies of , and a copy of , the complete graph on vertices with one missing edge. Erd\H{o}s asked if the same result is true for , the complete 3-uniform hypergraph on vertices. In this note we show that for small values of , the number of vertices in , the answer is negative for . For the second property, that of containing a , we show that for the answer is negative for all large as well, by proving that the Tur{\'a}n density of is greater than that of .
Cite
@article{arxiv.1111.5743,
title = {Two questions of Erd\H{o}s on hypergraphs above the Tur{\'a}n threshold}},
author = {Klas Markström},
journal= {arXiv preprint arXiv:1111.5743},
year = {2011}
}