Nordhaus-Gaddum-type Theorems for decompositions into many parts

نویسندگان

  • Zoltán Füredi
  • Alexandr V. Kostochka
  • Riste Skrekovski
  • Michael Stiebitz
  • Douglas B. West
چکیده

A k-decomposition (G1, . . . , Gk) of a graph G is a partition of its edge set to form k spanning subgraphs G1, . . . , Gk. The classical theorem of Nordhaus and Gaddum bounds χ(G1) + χ(G2) and χ(G1)χ(G2) over all 2-decompositions of Kn. For a graph parameter p, let p(k;G) denote the maximum of ∑k i=1 p(Gi) over all k-decompositions of the graph G. The clique number ω, chromatic number χ, list chromatic number χ`, and Szekeres–Wilf number σ satisfy ω(2;Kn) = χ(2;Kn) = χ`(2;Kn) = σ(2;Kn) = n + 1. We obtain lower and upper bounds for ω(k;Kn), χ(k;Kn), χ`(k;Kn), and σ(k;Kn). The last three behave differently for large k. We also obtain lower and upper bounds for the maximum of χ(k;G) over all graphs embedded on a given surface.

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عنوان ژورنال:
  • Journal of Graph Theory

دوره 50  شماره 

صفحات  -

تاریخ انتشار 2005