Generalized vertex-rankings of trees
β Scribed by Xiao Zhou; Nobuaki Nagai; Takao Nishizeki
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 622 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0020-0190
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π SIMILAR VOLUMES
It is proved that for any vector space W, any set of parafermion-like vertex operators on W in a certain canonical way generates a generalized vertex algebra in the sense of Dong and Lepowsky with W as a natural module. As an application, generalized vertex algebras are constructed from the Lepowsky
## Abstract The generalized RandiΔ; index ${R}\_{-\alpha}(T)$ of a tree __T__ is the sum over the edges ${u}{v}$ of __T__ of $(d(u)d(v))^{-\alpha}$ where ${d}(x)$ is the degree of the vertex __x__ in __T__. For all $\alpha > 0$, we find the minimal constant $\beta\_{0}=\beta\_{0}(\alpha)$ such that
In this paper, we introduce the problem of computing a minimum edge ranking spanning tree (MERST); i.e., find a spanning tree of a given graph G whose edge ranking is minimum. Although the minimum edge ranking of a given tree can be computed in polynomial time, we show that problem MERST is NP-hard.
## Abstract Let ${\cal G}^{s}\_{r}$ denote the set of graphs with each vertex of degree at least __r__ and at most __s__, __v__(__G__) the number of vertices, and Ο~__k__~ (__G__) the maximum number of disjoint __k__βedge trees in __G__. In this paper we show that if __G__ β ${\cal G}^{s}\_{2}$ a