To a graph G is canonically associated its neighborhood-hypergraph, X(G), formed by the closed neighborhoods of the vertices of G. We characterize the graphs G such that (i) X(G) has no induced cycle, or (ii) #(G) is a balanced hypergraph or (iii) X(G) is triangle free. (i) is another short proof of
A note on graphs whose neighborhoods aren-cycles
โ Scribed by Bruce L. Chilton; Ronald Gould; Albert D. Polimeni
- Publisher
- Springer
- Year
- 1974
- Tongue
- English
- Weight
- 220 KB
- Volume
- 3
- Category
- Article
- ISSN
- 0046-5755
No coin nor oath required. For personal study only.
โฆ Synopsis
AnSTRACr. Let G be a graph, and let v be a vertex of G. We denote by N(v) the set of vertices of G which are adjacent to v, and by (N(v)) the subgraph of G induced by N(v).
We call <N(v)) the neighborhood of v. In a paper of 1968, Agakishieva has, as one of her main theorems, the statement: "Graphs in which every neighborhood is an n-cycle exist if and only if 3 ~< n ~< 6.
๐ SIMILAR VOLUMES
Grossman and Ha ggkvist gave a sufficient condition under which a two-edgecoloured graph must have an alternating cycle (i.e., a cycle in which no two consecutive edges have the same colour). We extend their result to edge-coloured graphs with any number of colours. That is, we show that if there is
Tan, E.L., Some notes on cycle graphs, Discrete Mathematics 105 (1992) 221-226. The cycle graph C(G) of a graph G is the graph whose vertices are the chordless cycles of G and two vertices in C(G) are adjacent whenever the corresponding chordless cycles have at least one edge in common. If G is acyc