Packing of graphic n-tuples

نویسندگان

  • Arthur H. Busch
  • Michael Ferrara
  • Stephen G. Hartke
  • Michael S. Jacobson
  • Hemanshu Kaul
  • Douglas B. West
چکیده

An n-tuple π (not necessarily monotone) is graphic if there is a simple graph G with vertex set {v1, . . . , vn} in which the degree of vi is the ith entry of π. Graphic n-tuples (d (1) 1 , . . . , d (1) n ) and (d (2) 1 , . . . , d (2) n ) pack if there are edge-disjoint n-vertex graphs G1 and G2 such that dG1(vi) = d (1) i and dG2(vi) = d (2) i for all i. We prove that graphic n-tuples π1 and π2 pack if ∆ ≤ √ 2δn− (δ − 1), where ∆ and δ denote the largest and smallest entries in π1 + π2 (strict inequality when δ = 1); also, the bound is sharp. Kundu and Lovász independently proved that a graphic n-tuple π is realized by a graph with a k-factor if the n-tuple obtained by subtracting k from each entry of π is graphic; for even n we conjecture that in fact some realization has k edge-disjoint 1-factors. We prove the conjecture in the case where the largest entry of π is at most n/2 + 1 and also when k ≤ 3.

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عنوان ژورنال:
  • Journal of Graph Theory

دوره 70  شماره 

صفحات  -

تاریخ انتشار 2012