We give necessary and sufficient conditions for a directed graph embedded on the torus or the Klein bottle to contain pairwise disjoint circuits, each of a given orientation and homotopy, and in a given order. For the Klein bottle, the theorem is new. For the torus, the theorem was proved before by
Spanning Planar Subgraphs of Graphs in the Torus and Klein Bottle
β Scribed by R. Brunet; M.N. Ellingham; Z.C. Gao; A. Metzlar; R.B. Richter
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 685 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0095-8956
No coin nor oath required. For personal study only.
β¦ Synopsis
There are two main purposes of this article. First we show that every 3-connected graph embedded in the torus or the Klein bottle has a spanning planar subgraph which is 2-connected, and in fact has a slightly stronger connectivity property. Second, this subgraph is applied to show that every 3-connected graph that embeds in the torus or Klein bottle has both a 2-walk (a closed walk visiting every vertex exactly once or twice) and a 3-tree (a spanning tree with maximum degree at most 3). This completes the characterization of surfaces for which every embedded 3-connected graph has a 2-walk (or 3-tree). , 1995 Academic Press. Inc.
π SIMILAR VOLUMES
## Abstract Thomassen conjectured that every longest circuit of a 3βconnected graph has a chord. It is proved in this paper that every longest circuit of a 4βconnected graph embedded in a torus or Klein bottle has a chord. Β© 2003 Wiley Periodicals, Inc. J Graph Theory 43: 1β23, 2003
We show how to construct all the graphs that can be embedded on both the torus and the Klein bottle as their triangulations.
## Abstract It is shown that a connected graph __G__ spans an eulerian graph if and only if __G__ is not spanned by an odd complete bigraph __K__(2~m~ + 1, 2__n__ + 1). A disconnected graph spans an eulerian graph if and only if it is not the union of the trivial graph with a complete graph of odd
## Abstract Let __G__ be a graph embedded in the Klein bottle with βrepresentativityβ at least four. We give a formula for the orientable genus of __G__, which also implies a polynomially bounded algorithm. The formula is in terms of the number of times certain closed curves on the Klein bottle int