1,224 research outputs found
The asymptotic covering density of generalized Petersen graphs
Remark on the paper "Minimum vertex covers in the generalized Petersen
graphs P(n; 2)" by M. Behzad, P. Hatami, and E.S. MahmoodianDedicated to Tomaz Pisanski on the occasion of his 60th birthdayThe covering density of a graph G=(V,E) is delta(G)= beta(G)/|V|where beta(G), the covering number, is the minimum number of vertices that represent all edges of G. The asymptotic covering density of the generalized Petersen graph is determined
A Variation of Decomposition Under a Length Constraint
Introducing and initiating a study of a new variation of decomposition namely equiparity induced path decomposition of a graph which is defined to be a decomposition in which all the members are induced paths having same parity
Generation and Properties of Snarks
For many of the unsolved problems concerning cycles and matchings in graphs
it is known that it is sufficient to prove them for \emph{snarks}, the class of
nontrivial 3-regular graphs which cannot be 3-edge coloured. In the first part
of this paper we present a new algorithm for generating all non-isomorphic
snarks of a given order. Our implementation of the new algorithm is 14 times
faster than previous programs for generating snarks, and 29 times faster for
generating weak snarks. Using this program we have generated all non-isomorphic
snarks on vertices. Previously lists up to vertices have been
published. In the second part of the paper we analyze the sets of generated
snarks with respect to a number of properties and conjectures. We find that
some of the strongest versions of the cycle double cover conjecture hold for
all snarks of these orders, as does Jaeger's Petersen colouring conjecture,
which in turn implies that Fulkerson's conjecture has no small counterexamples.
In contrast to these positive results we also find counterexamples to eight
previously published conjectures concerning cycle coverings and the general
cycle structure of cubic graphs.Comment: Submitted for publication V2: various corrections V3: Figures updated
and typos corrected. This version differs from the published one in that the
Arxiv-version has data about the automorphisms of snarks; Journal of
Combinatorial Theory. Series B. 201
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