The Kneser graph K (n, k) has as its vertex set all k-subsets of an n-set and two k-subsets are adjacent if they are disjoint. The odd graph O k is a special case of Kneser graph when n = 2k +1. A long standing conjecture claims that O k is hamiltonian for all k>2. We show that the prism over O k is
The prism-free planar graphs and their cycles bases
β Scribed by David Hartvigsen; Russell Mardon
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 501 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0364-9024
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β¦ Synopsis
Abstract
Dirac (1962) showed that the planar graphs with no prism minor are the graphs obtainable by 2βsums from bonds, cycles, wheels and K~5~_e_'s. We give a new characterization of these graphs in terms of an optimization problem defined on the cycle bases of a graph.
π SIMILAR VOLUMES
XBSTRACT: A number of interesting properties of a cycle-free directed graph are presented By making use of these properties an e.Oicient algorithm is deduced which identifies the longest path, or the Hamiltonian path if any, between every pair of vertices. The properties are expressed in terms of th
We investigate some properties of graphs whose cycle space has a basis constituted of triangles ('null-homotopic' graphs). We obtain characterizations in the case of planar graphs, and more generally, of graphs not contractible onto Ks. These characterizations involve separating subsets and decompos
## Abstract Every 3βconnected planar, cubic, triangleβfree graph with __n__ vertices has a bipartite subgraph with at least 29__n__/24βββ7/6 edges. The constant 29/24 improves the previously best known constant 6/5 which was considered best possible because of the graph of the dodecahedron. Example