## Abstract It is shown that if __G__ is a 3‐connected graph with |__V(G)__| ≥ 10, then, with the exception of one infinite class based on __K__~3,__p__~, it takes at least four vertices to cover the set of contractible edges of __G__. © 1993 John Wiley & Sons, Inc.
Covering contractible edges in 3-connected graphs. I: Covers of size three are cutsets
✍ Scribed by Akira Saito
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 397 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
An edge of a 3‐connected graph is said to be contractible if its contraction results in a 3‐connected graph. In this paper, a covering of contractible edges is studied. We give an alternative proof to the result of Ota and Saito (Scientia (A) 2 (1988) 101–105) that the set of contractible edges in a 3‐connected graph cannot be covered by two vertices, and extended this result to a three‐vertex covering. We also study the existence of a contractible edge whose contraction preserves a specified cycle, and show that a non‐hamiltonian 3‐connected graph has a contractible edge whose contraction preserves the circumference.
📜 SIMILAR VOLUMES
## Abstract In this paper, we show that if a 3‐connected graph __G__ other than __K__~4~ has a vertex subset __K__ that covers the set of contractible edges of __G__ and if |__K__| 3 and |__V(G)__| 3|__K__| − 1, then __K__ is a cutset of __G__. We also give examples to show that this result is best