English

Positive co-degree Tur\'an number for $C_5$ and $C_5^{-}$

Combinatorics 2022-12-27 v1

Abstract

The \emph{minimum positive co-degree} δr1+(H)\delta^{+}_{r-1}(H) of a non-empty rr-graph HH is the maximum kk such that if SS is an (r1)(r-1)-set contained in a hyperedge of HH, then SS is contained in at least kk hyperedges of HH. For any rr-graph FF, the \emph{positive degree Tur\'an number} co+ex(n,F)\mathrm{co}^{+}\mathrm{ex}(n,F) is defined as the maximum value of δr1+(H)\delta^{+}_{r-1}(H) over all nn-vertex FF-free non-empty rr-graphs HH. In this paper, we determine the positive degree Tur\'an number for C5C_5 and C5C_5^{-}.

Keywords

Cite

@article{arxiv.2212.12815,
  title  = {Positive co-degree Tur\'an number for $C_5$ and $C_5^{-}$},
  author = {Zhuo Wu},
  journal= {arXiv preprint arXiv:2212.12815},
  year   = {2022}
}

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8 pages