1. THE TURÁN NUMBER OF BERGE-K4 IN 3-UNIFORM HYPERGRAPHS.
- Author
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HUI ZHU, LIYING KANG, ZHENYU NI, and ERFANG SHAN
- Subjects
BIJECTIONS ,MATHEMATICS ,HYPERGRAPHS ,EVIDENCE ,EDGES (Geometry) - Abstract
For a graph G = (V,E), a hypergraph H is called a Berge-G if there is a bijection f : E(G) → E(H) such that e ⊆ f(e) for all e ∈ E(G). The family of Berge-G hypergraphs is denoted by B(G). The maximum number of edges in an n-vertex r-graph with no subhypergraph isomorphic to any Berge-G is denoted by ex
r (n, B (G)). Gyárfás [SIAM J. Discrete Math., 33 (2019), pp. 383-- 392] showed that for n ≥ 6, ex3(n, B (K4)) = [n/3] [n+1/3] [n+2/3]. However, we found an error in the proof of the result when n ≥ 7. A recent result due to Gerbner, Methuku, and Palmer [European J. Combin., 86 (2020), 103082] implies that for n ≥ 9, ex3 (n, B (K4)) = [n/3] [n+1/3] [n+2/3]. In this paper we prove the remaining cases n = 7 and n = 8 for the completeness of the conclusion. [ABSTRACT FROM AUTHOR]- Published
- 2020
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