A nowhere-zero 3-flow in a graph G is an assignment of a direction and a value of 1 or 2 to each edge of G such that, for each vertex v in G, the sum of the values of the edges with tail v equals the sum of the values of the edges with head v. Motivated by results about the region coloring of planar
Nowhere-zero 3-flows in locally connected graphs
✍ Scribed by Hong-Jian Lai
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 91 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
Let G be a graph. For each vertex v ∈V(G), N~v~ denotes the subgraph induces by the vertices adjacent to v in G. The graph G is locally k‐edge‐connected if for each vertex v ∈V(G), N~v~ is k‐edge‐connected. In this paper we study the existence of nowhere‐zero 3‐flows in locally k‐edge‐connected graphs. In particular, we show that every 2‐edge‐connected, locally 3‐edge‐connected graph admits a nowhere‐zero 3‐flow. This result is best possible in the sense that there exists an infinite family of 2‐edge‐connected, locally 2‐edge‐connected graphs each of which does not have a 3‐NZF. © 2003 Wiley Periodicals, Inc. J Graph Theory 42: 211–219, 2003
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