Graphs with the same peripheral and center eccentric vertices
The eccentricity of a vertex is the distance from to a vertex farthest from , and is an eccentric vertex for if its distance from is . A vertex of maximum eccentricity in a graph is called peripheral, and the set of all such vertices is the peripherian, denoted . We use to denote the set of eccentric vertices of vertices in . A graph is called an S-graph if . In this paper we characterize S-graphs with diameters less or equal to four, give some constructions of S-graphs and...