Critical chromatic number and the complexity of perfect packings in graphs

  • Authors:
  • Daniela Kühn;Deryk Osthus

  • Affiliations:
  • Birmingham University, Edgbaston, UK;Birmingham University, Edgbaston, UK

  • Venue:
  • SODA '06 Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm
  • Year:
  • 2006

Quantified Score

Hi-index 0.00

Visualization

Abstract

Let H be any non-bipartite graph. We determine asymptotically the minimum degree of a graph G which ensures that G has a perfect H-packing. More precisely, we determine the smallest number τ having the following property: For every positive constant γ there exists an integer n0 = n0(γ, H) such that every graph G whose order n ≥n0 is divisible by |H| and whose minimum degree is at least (τ + γ) n contains a perfect H-packing. The value of τ depends on the relative sizes of the colour classes in the optimal colourings of H. The proof is algorithmic, which shows that the problem of finding a maximum H-packing is polynomially solvable for graphs G whose minimum degree is at least (τ + γ)n. On the other hand, given any positive constant γ, we show that for infinitely many (non-bipartite) graphs H the corresponding decision problem becomes NP-complete if one considers input graphs G of minimum degree at least (τ - γ)n.