Abstract In this paper, the exact formulae for the Harary indices of join, disjunction, symmetric difference, strong product of graphs are obtained. Also, the Schultz and modified Schultz indices of join and strong product of graphs are computed. We apply some of our results to compute the Harary, Schultz and modified Schultz indices of fan graph, wheel graph, open fence and closed fence graphs.

Symmetric properties of some molecular graphs on the torus are studied. In particular we determine which cubic cyclic Haar graphs are 1-regular, which is equivalent to saying that their line graphs are 1 2-arc-transitive. Although these symmetries make all vertices and all edges indistinguishable , they imply intrinsic chirality of the corresponding molecular graph.

This paper has two main parts. First, we consider the Tutte symmetric function XB, a generalization of chromatic function. We introduce vertex-weighted version XB and show that this admits deletion-contraction relation. also demonstrate spanning-tree spanning-forest expansions generalizing those polynomial by connecting to other graph functions. Second, give several methods for constructing non...

Let r be finite connected and G a group of automorphisms of r which is transitive on vertices. Suppose that, for a vertex 0 of r, S ~ G~(O') ::; Aut S for some simple group S with S acting primitively on the set r( a) of neighbours of 0, and suppose that G is minimal with these properties. Then one of: (i) G is a nonabelian simple group, (ii) r is a Cayley graph for a normal subgroup N of G and...

A symmetric matroid is a matroid deened on the edge-set of some countably innnite complete graph K in a way that ranks of nite sub-graphs of K are invariant under isomorphism. Thus a symmetric ma-troid M induces on any nite graph G a uniquely determined matroid M(G). We study connectivity properties of circuits and generalized trees of symmetric matroids. We give several characterizations of a ...

The k-th power of a n-vertex graph X is the iterated cartesian product of X with itself. The k-th symmetric power of X is the quotient graph of certain subgraph of its k-th power by the natural action of the symmetric group. It is natural to ask if the spectrum of the k-th power –or the spectrum of the k-th symmetric power– is a complete graph invariant for small values of k, for example, for k...

We consider the class of I-graphs I(n, j, k), which is a generalization over the class of the generalized Petersen graphs. We study different properties of I-graphs such as connectedness, girth and whether they are bipartite or vertex-transitive. We give an efficient test for isomorphism of I-graphs and characterize the automorphism groups of I-graphs. Regular bipartite graphs with girth at lea...

For a connected pasting scheme G, under reasonable assumptions on the underlying category, the category of C-colored G-props admits a cofibrantly generated model category structure. In this paper, we show that, if G is closed under shrinking internal edges, then this model structure on G-props satisfies a (weaker version) of left properness. Connected pasting schemes satisfying this property in...

The generalized Petersen graphs (GPGs) which have been invented by Watkins, may serve for perhaps the simplest nontrivial examples of “galactic” graphs, i.e. those with a nice property of having a semiregular automorphism. Some of them are also vertextransitive or even more highly symmetric, and some are Cayley graphs. In this paper, we study a further extension of the notion of GPGs with the e...