Let G be a 2-edge-connected undirected graph, A be an (additive) abelian group and A∗ = A−{0}. A graph G is A-connected if G has an orientation D(G) such that for every function b : V (G) 7→ A satisfying ∑ v∈V (G) b(v) = 0, there is a function f : E(G) 7→ A ∗ such that for each vertex v ∈ V (G), the total amount of f values on the edges directed out from v minus the total amount of f values on ...

Let G be a graph. The connectivity of G, κ(G), is the maximum integer k such that there exists a k-container between any two different vertices. A k-container of G between u and v, Ck(u, v), is a set of k-internally-disjoint paths between u and v. A spanning container is a container that spans V (G). A graph G is k-connected if there exists a spanning k-container between any two different verti...

Let G be a 2-edge-connected undirected graph, A be an (additive) Abelian group, and A = A − {0}. A graph G is A-connected if G has an orientation D(G) such that for every mapping b: V (G) → A satisfying  v∈V (G) b(v) = 0, there is a function f : E(G) → A ∗ such that for each vertex v ∈ V (G), the sum of f over the edges directed out from v minus the sum of f over the edges directed into v eq...

Let $G=(V,E)$ be a simple connected graph. A perfect matching (or Kekul'e structure in chemical literature) of $G$ is a set of disjoint edges which covers all vertices of $G$. The anti-forcing number of $G$ is the smallest number of edges such that the remaining graph obtained by deleting these edges has a unique perfect matching and is denoted by $af(G)$. In this paper we consider some specifi...

For a 2-factor F of a connected graph G, we consider G − F , which is the graph obtained from G by removing all the edges of F . If G − F is connected, F is said to be a non-separating 2-factor. In this paper we study a sufficient condition for a 2r -regular connected graph G to have such a 2-factor. As a result, we show that a 2r -regular connected graph G has a non-separating 2-factor wheneve...

‎darafsheh and assari in [normal edge-transitive cayley graphs on non-abelian groups of order 4p‎, ‎where $p$ is a prime number‎, ‎sci‎. ‎china math‎., ‎56 (1) (2013) 213-219.] classified the connected normal edge transitive and‎ ‎$frac{1}{2}-$arc-transitive cayley graph of groups of order $4p$‎. ‎in this paper we continue this work by classifying the‎ ‎connected cayley graph of groups of order...

A graph G is Eulerian-connected if for any u and v in V (G), G has a spanning (u. v)-trail. A graph G is edge-Eulerian-connected if for any e' and elf in E(G), G has a spanning (e', elf)-trail. For an integer r ~ 0, a graph is called r-Eulerian-connected if for any X s::: E(G) with IXI ~r, and for any u, v E V(G), G has a spanning (u, v)-trail T such that X s::: E(T). The r-edge-Eulerian­ conne...

A dominating set D of a graph G is a subset of V (G) such that for every vertex v ∈ V (G), either v ∈ D or there exists a vertex u ∈ D that is adjacent to v in G. Dominating sets of small cardinality are of interest. A connected dominating set C of a graph G is a dominating set of G such that the subgraph induced by the vertices of C in G is connected. A weakly-connected dominating set W of a g...

general formulas are obtained for the vertex padmakar-ivan index (piv) of tetrathiafulvalene(ttf) dendrimer, whereby ttf units we are employed as branching centers. the piv index isa wiener-szeged-like index developed very recently. this topological index is defined as thesummation of all sums of nu(e) and nv(e), over all edges of connected graph g.