Displaying similar documents to “On generating snarks”

Cyclically 5-edge connected non-bicritical critical snarks

Stefan Grünewald, Eckhard Steffen (1999)

Discussiones Mathematicae Graph Theory

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Snarks are bridgeless cubic graphs with chromatic index χ' = 4. A snark G is called critical if χ'(G-{v,w}) = 3, for any two adjacent vertices v and w. For any k ≥ 2 we construct cyclically 5-edge connected critical snarks G having an independent set I of at least k vertices such that χ'(G-I) = 4. For k = 2 this solves a problem of Nedela and Skoviera [6].

Mácajová and Škoviera conjecture on cubic graphs

Jean-Luc Fouquet, Jean-Marie Vanherpe (2010)

Discussiones Mathematicae Graph Theory

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A conjecture of Mácajová and Skoviera asserts that every bridgeless cubic graph has two perfect matchings whose intersection does not contain any odd edge cut. We prove this conjecture for graphs with few vertices and we give a stronger result for traceable graphs.

Sharp Upper Bounds for Generalized Edge-Connectivity of Product Graphs

Yuefang Sun (2016)

Discussiones Mathematicae Graph Theory

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The generalized k-connectivity κk(G) of a graph G was introduced by Hager in 1985. As a natural counterpart of this concept, Li et al. in 2011 introduced the concept of generalized k-edge-connectivity which is defined as λk(G) = min{λ(S) : S ⊆ V (G) and |S| = k}, where λ(S) denote the maximum number ℓ of pairwise edge-disjoint trees T1, T2, . . . , Tℓ in G such that S ⊆ V (Ti) for 1 ≤ i ≤ ℓ. In this paper, we study the generalized edge- connectivity of product graphs and obtain sharp...

Some recent results on domination in graphs

Michael D. Plummer (2006)

Discussiones Mathematicae Graph Theory

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In this paper, we survey some new results in four areas of domination in graphs, namely: (1) the toughness and matching structure of graphs having domination number 3 and which are "critical" in the sense that if one adds any missing edge, the domination number falls to 2; (2) the matching structure of graphs having domination number 3 and which are "critical" in the sense that if one deletes any vertex, the domination number falls to 2; ...

A magical approach to some labeling conjectures

Ramon M. Figueroa-Centeno, Rikio Ichishima, Francesc A. Muntaner-Batle, Akito Oshima (2011)

Discussiones Mathematicae Graph Theory

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In this paper, a complete characterization of the (super) edge-magic linear forests with two components is provided. In the process of establishing this characterization, the super edge-magic, harmonious, sequential and felicitous properties of certain 2-regular graphs are investigated, and several results on super edge-magic and felicitous labelings of unions of cycles and paths are presented. These labelings resolve one conjecture on harmonious graphs as a corollary, and make headway...

The edge geodetic number and Cartesian product of graphs

A.P. Santhakumaran, S.V. Ullas Chandran (2010)

Discussiones Mathematicae Graph Theory

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For a nontrivial connected graph G = (V(G),E(G)), a set S⊆ V(G) is called an edge geodetic set of G if every edge of G is contained in a geodesic joining some pair of vertices in S. The edge geodetic number g₁(G) of G is the minimum order of its edge geodetic sets. Bounds for the edge geodetic number of Cartesian product graphs are proved and improved upper bounds are determined for a special class of graphs. Exact values of the edge geodetic number of Cartesian product are obtained...