English

A hypergraph analog of Dirac's Theorem for long cycles in 2-connected graphs

Combinatorics 2024-03-01 v3

Abstract

Dirac proved that each nn-vertex 22-connected graph with minimum degree at least kk contains a cycle of length at least min{2k,n}\min\{2k, n\}. We consider a hypergraph version of this result. A Berge cycle in a hypergraph is an alternating sequence of distinct vertices and edges v1,e2,v2,,ec,v1v_1,e_2,v_2, \ldots, e_c, v_1 such that {vi,vi+1}ei\{v_i,v_{i+1}\} \subseteq e_i for all ii (with indices taken modulo cc). We prove that for nkr+25n \geq k \geq r+2 \geq 5, every 22-connected rr-uniform nn-vertex hypergraph with minimum degree at least (k1r1)+1{k-1 \choose r-1} + 1 has a Berge cycle of length at least min{2k,n}\min\{2k, n\}. The bound is exact for all kr+25k\geq r+2\geq 5.

Keywords

Cite

@article{arxiv.2212.14516,
  title  = {A hypergraph analog of Dirac's Theorem for long cycles in 2-connected graphs},
  author = {Alexandr Kostochka and Ruth Luo and Grace McCourt},
  journal= {arXiv preprint arXiv:2212.14516},
  year   = {2024}
}

Comments

23 pages, 2 figures