A lower bound for the CO-irredundance number of a graph Original Research Article

This paper establishes a necessary and sufficient condition for a CO-irredundant set of vertices of a graph to be maximal and shows that the smallest cardinality of a maximal CO-irredundant set in an n vertex graph with maximum degree image is bounded below by image for image, image for image and image for image. This result is best possible and extremal graphs are characterised for image.