Resistance distance and Kirchhoff index in generalized R-vertex and R-edge corona for graphs
For a graph G, the graph R(G) of a graph G is the graph obtained by adding a new vertex for each edge of G and joining each new vertex to both end vertices of the corresponding edge. Let I(G) be the set of newly added vertices, i.e I(G) = V(R(G))\ V(G). The generalized R-vertex corona of G and Hi for i = 1, 2, ?,n, denoted by R(G) ?? ^n i=1 Hi, is the graph obtained from R(G) and Hi by joining the i-th vertex of V(G) to every vertex in Hi. The generalized R-edge corona of G and Hi for i = 1, 2, ?,m, denoted by R(G)?^m i=1 Hi, is the graph obtained from R(G) and Hi by joining the i-th vertex of I(G) to every vertex in Hi. In this paper, we derive closed-form formulas for resistance distance and Kirchhoff index of R(G) ?? ^n i=1 Hi and R(G) ? ^m i=1 Hi whenever G and Hi are arbitrary graphs. These results generalize the existing results.