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research-article

Tiling multipartite hypergraphs in quasi-random hypergraphs

Published: 01 May 2023 Publication History

Abstract

Given k ≥ 2 and two k-graphs (k-uniform hypergraphs) F and H, an F-factor in H is a set of vertex disjoint copies of F that together covers the vertex set of H. Lenz and Mubayi studied the F-factor problems in quasi-random k-graphs with minimum degree Ω ( n k − 1 ). In particular, they constructed a sequence of 1/8-dense quasi-random 3-graphs H ( n ) with minimum degree Ω ( n 2 ) and minimum codegree Ω ( n ) but with no K 2, 2, 2-factor. We prove that if p > 1 / 8 and F is a 3-partite 3-graph with f vertices, then for sufficiently large n, all p-dense quasi-random 3-graphs of order n with minimum codegree Ω ( n ) and f | n have F-factors. That is, 1/8 is the density threshold for ensuring all 3-partite 3-graphs F-factors in quasi-random 3-graphs given a minimum codegree condition Ω ( n ). Moreover, we show that one can not replace the minimum codegree condition by a minimum vertex degree condition. In fact, we find that for any p ∈ ( 0, 1 ) and n ≥ n 0, there exist p-dense quasi-random 3-graphs of order n with minimum degree Ω ( n 2 ) having no K 2, 2, 2-factor. In particular, we study the optimal density threshold of F-factors for each 3-partite 3-graph F in quasi-random 3-graphs given a minimum codegree condition Ω ( n ).
In addition, we also study F-factor problems for k-partite k-graphs F with stronger quasi-random assumption and minimum degree Ω ( n k − 1 ).

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Published In

cover image Journal of Combinatorial Theory Series B
Journal of Combinatorial Theory Series B  Volume 160, Issue C
May 2023
215 pages

Publisher

Academic Press, Inc.

United States

Publication History

Published: 01 May 2023

Author Tags

  1. Multipartite hypergraph
  2. Quasi-random hypergraph
  3. F-factor
  4. Absorbing method

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