• ON BLOCK LINE GRAPHS, MIDDLE LINE GRAPHS AND MIDDLE BLOCK GRAPHS

Abstract

In this paper, we introduce the concepts of (i) the block line graph of a graph (ii) the middle line graph of a graph and (iii) the middle block graph of a graph. We obtain some properties of these graphs. We present characterizations of graphs whose block line graphs and middle line graphs are isomorphic, (ii) whose block line graphs and middle block graphs are isomorphic and (iii) whose middle line graphs and middle block graphs are isomorphic.