Graphs with least eigenvalue -2 attaining a convex quadratic upper bound for th...

• Author(s): Cardoso, Domingos M. ; Cvetkovic, D.
• Date: 2006
• Persistent ID: http://hdl.handle.net/10773/4441
• Origin: RIA - Repositório Institucional da Universidade de Aveiro
• Subject(s): Graph theory; Graph spectra; Line graph; Quadratic programming; Stability number
• Document Type: Article
• Language: English

Description

In this paper we study the conditions under which the stability number of line graphs, generalized line graphs and exceptional graphs attains a convex quadratic programming upper bound. In regular graphs this bound is reduced to the well known Hoffman bound. Some vertex subsets inducing subgraphs with regularity properties are analyzed. Based on an observation concerning the Hoffman bound a new construction of regular exceptional graphs is provided. CEOC FCT FEDER