An edge-colored graph G, where adjacent edges may be colored the same, is rainbow connected if any two vertices of G are connected by a path whose edges have distinct colors. The rainbow connection number rc(G) of a connected graph G is the smallest number of colors that are needed in order to make G rainbow connected. In this paper, we give a sharp upper bound that rc(G) ≤ ⌈n2 ⌉ for any 2-conn...

An edge colored graph G is rainbow edge connected if any two vertices are connected by a path whose edges have distinct colors. The rainbow connectivity of a connected graph G, denoted by rc(G), is the smallest number of colors that are needed in order to make G rainbow connected. In this work we study the rainbow connectivity of the binomial graph G = G(n, p) at the connectivity threshold p = ...

Rainbow connection number rc(G) of a connected graph G is the minimum number of colours needed to colour the edges of G, so that every pair of vertices is connected by at least one path in which no two edges are coloured the same. In this paper we show that for every connected graph G, with minimum degree at least 2, the rainbow connection number is upper bounded by γc(G) + 2, where γc(G) is th...

The open neighborhood NG(e) of an edge e in a graph G is the set consisting of all edges having a common end-vertex with e and its closed neighborhood is NG[e] = NG(e) ∪ {e}. Let f be a function on E(G), the edge set of G, into the set {−1, 1}. If ∑x∈NG[e] f(x) ≥ 1 for at least a half of the edges e ∈ E(G), then f is called a signed edge majority dominating function of G. The minimum of the val...

In the article, the existence of rainbow cycles in edge colored plane triangulations is studied. It is shown that the minimum number rb(Tn,C3) of colors that force the existence of a rainbow C3 in any n-vertex plane triangulation is equal to 3n−4 2 . For k ≥ 4 a lower bound and for k ∈ {4,5} an upper bound of the number rb(Tn,Ck ) is determined. C © 2014 Wiley Periodicals, Inc. J. Graph Theory ...

Bipartite graphs with equal edge domination number and maximum matching cardinality are characterized. These two parameters are used to develop bounds on the vertex cover and total vertex cover numbers of graphs and a resulting chain of vertex covering, edge domination, and matching parameters is explored. In addition, the total vertex cover number is compared to the total domination number of ...

For any graph, there is a largest integer k such that given any partition of the vertex set with at most k elements in each class of the partition, there is transversal of the partition that is a dominating set in the graph. Some basic results about this parameter, the partition domination number, are obtained. In particular, it is shown that its value is 2 for the two-dimensional infinite grid...

In this paper, we present an improved algorithm to decide whether a graph of maximum degree 3 has an edge dominating set of size k or not, which is based on enumerating vertex covers. We first enumerate vertex covers of size at most 2k and then construct an edge dominating set based on each vertex cover to find a satisfied edge dominating set. To enumerate vertex covers, we use a branch-and-red...

We present an O∗(1.3160n)-time algorithm for the edge dominating set problem in an n-vertex graph, which improves previous exact algorithms for this problem. The algorithm is analyzed by using the “Measure and Conquer method.” We design new branching rules based on conceptually simple local structures, called “clique-producing vertices/cycles,” which significantly simplify the algorithm and its...

A path in an edge-colored graph is called a monochromatic if all edges of the have same color. We call k paths \(P_1,\ldots ,P_k\) rainbow every \(P_i\) and for any two \(i\ne j\), \(P_j\) different colors. An edge-coloring G said to be k-edge-connection coloring (or \(RMC_k\)-coloring short) distinct vertices are connected by at least paths. use \(rmc_k(G)\) denote maximum number colors that e...