Please cite this article in press as: K. Xu et al., Some extremal results on the connective eccentricity index of graphs, J. Math. Anal. Appl. (2015), http://dx.
AbstractThe connective eccentricity index (CEI) of a graph G is defined asare the eccentricity and the degree of vertex v i , respectively, in G. In this paper we obtain some lower and upper bounds on the connective eccentricity index for all trees of order n and with matching number β and characterize the corresponding extremal trees. And the maximal graphs of order n and with matching number β and n edges have been determined which maximize the connective eccentricity index. Also the extremal graphs with maximal connective eccentricity index are completely characterized among all connected graphs of order n and with matching number β. Moreover we establish some relations between connective eccentricity index and eccentric connectivity index, as another eccentricity-based invariant, of graphs. AMS classification (2010): 05C07, 05C12, 05C35