We describe a new type of sufficient condition for a digraph to be Hamiltonian. Conditions of this type combine local structure of the digraph with conditions on the degrees of nonadjacent vertices. The main difference from earlier conditions is that we do not require a degree condition on all pairs
Quasi-Hamiltonicity: A Series of Necessary Conditions for a Digraph to Be Hamiltonian
β Scribed by Gregory Gutin; Anders Yeo
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 129 KB
- Volume
- 78
- Category
- Article
- ISSN
- 0095-8956
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β¦ Synopsis
We introduce new necessary conditions, k-quasi-hamiltonicity (0 k n&1), for a digraph of order n to be hamiltonian. Every (k+1)-quasi-hamiltonian digraph is also k-quasi-hamiltonian; we construct digraphs which are k-quasi-hamiltonian, but not (k+1)-quasi-hamiltonian. We design an algorithm that checks k-quasihamiltonicity of a given digraph with n vertices and m arcs in time O(nm k ). We prove that (n&1)-quasi-hamiltonicity coincides with hamiltonicity and 1-quasihamiltonicity is equivalent to pseudo-hamiltonicity introduced (for undirected graphs) by L. Babel and G.
π SIMILAR VOLUMES
We prove the following conjecture of Broersma and Veldman: A connected, locally k-connected K,,-free graph is k-hamiltonian if and only if it is (k + 2)-connected ( k L 1). We use [ 11 for basic terminology and notation, and consider simple graphs only. Let G be a graph. By V(G) and E(G) we denote,
## Abstract Necessary and sufficient conditions for a fourth order functional differential equation of the form (1) [r(t)yβ³(t)]β³+f(t,y(h~1~(t)), y(h~2~(t)), β¦, y(h~n~(t)))=0 to be oscillatory are given when f is strongly superlinear or strongly sublinear.
It is shown that every solution of the nonhomogeneous functional differential equation x t y px t y q Q t G x t y s f t ,