Dirac proved that if each vertex of a graph G of order n 23 has degree at least n/2, then the graph is Hamiltonian. This result will be generalized by showing that if the union of the neighborhoods of each pair of vertices of a 2connected graph G of sufficiently large order n has at least n/2 vertic
A generalization of Ore's Theorem involving neighborhood unions
✍ Scribed by H.J. Broersma; J. van den Heuvel; H.J. Veldman
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 656 KB
- Volume
- 122
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
✦ Synopsis
Let G be a graph of order n. Settling conjectures of Chen and Jackson, we prove the following generalization of Ore's Theorem: If G is 2-connected and )N(u)u N(v)1 >:n for every pair of nonadjacent vertices a, u, then either G is hamiltonian, or G is the Petersen graph, or G belongs to one of three families of exceptional graphs of connectivity 2.
📜 SIMILAR VOLUMES
## Abstract In this paper, we obtain an asymptotic generalization of Turán's theorem. We prove that if all the non‐trivial eigenvalues of a __d__‐regular graph __G__ on __n__ vertices are sufficiently small, then the largest __K__~__t__~‐free subgraph of __G__ contains approximately (__t__ − 2)/(__
Let 9 be the polyhedron given by 9 = {x E R": Nx=O, a~x~b}, where N is a totally unimodular matrix and a and 6 are any integral vectors. For x E R" let (x)' denote the vector obtained from x by changing all its negative components to zeros. Let x1, . . . , xp be the integral points in 9 and let 9+ b
The following theorem is lproved. If the sets VI, . . . , Vn+, CR" and a E fly:: conv Vi, then there exist elements ui E Vi (i = 1, . . . , n + 1) such that a E conv{o,, . . . , un+J. Thii is a generalization of Carathtidory's theorem. By applying this and similar results some open questions are ans