Non-zero disjoint cycles in highly connected group labelled graphs

  • Authors:
  • Ken-ichi Kawarabayashi;Paul Wollan

  • Affiliations:
  • Graduate School of Information Sciences (GSIS), Tohoku University, Aramaki aza Aoba 09, Aoba-ku Sendai, Miyagi 980-8579, Japan;School of Mathematics, Georgia Institute of Technology, Atlanta, GA 30332, USA

  • Venue:
  • Journal of Combinatorial Theory Series B
  • Year:
  • 2006

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Abstract

Let G=(V,E) be an oriented graph whose edges are labelled by the elements of a group @C. A cycle C in G has non-zero weight if for a given orientation of the cycle, when we add the labels of the forward directed edges and subtract the labels of the reverse directed edges, the total is non-zero. We are specifically interested in the maximum number of vertex disjoint non-zero cycles. We prove that if G is a @C-labelled graph and G@? is the corresponding undirected graph, then if G@? is 312k-connected, either G has k disjoint non-zero cycles or it has a vertex set Q of order at most 2k-2 such that G-Q has no non-zero cycles. The bound ''2k-2'' is best possible. This generalizes the results due to Thomassen (The Erdos-Posa property for odd cycles in graphs with large connectivity, Combinatorica 21 (2001) 321-333.), Rautenbach and Reed (The Erdos-Posa property for odd cycles in highly connected graphs, Combinatorica 21 (2001) 267-278.) and Kawarabayashi and Reed (Highly parity linked graphs, preprint.), respectively.