We show that any properly edge-colored Kn contains a rainbow cycle with at least (4/7− o(1))n edges. This improves the lower bound of n/2− 1 proved in [1]. We consider properly edge-colored complete graphs Kn, where two edges with the same color cannot be incident to each other, so each color class is a matching. An important and well investigated special case of proper edge-colorings is a fact...

Let G = (V,E) be a graph and let f be a function f : E → {0, 1, 2}. An edge x with f(x) = 0 is said to be undefended with respect to f if it is not incident to an edge with positive weight. The function f is a weak edge Roman dominating function (WERDF) if each edge x with f(x) = 0 is incident to an edge y with f(y) > 0 such that the function f ′ : E → {0, 1, 2}, defined by f ′(x) = 1, f ′(y) =...

Let G be a graph of order n with an edge coloring c, and let δ(G) denote the minimum color degree of G, i.e., the largest integer such that each vertex of G is incident with at least δ(G) edges having pairwise distinct colors. A subgraph F ⊂ G is rainbow if all edges of F have pairwise distinct colors. In this paper, we prove that (i) if G is triangle-free and δ(G) > n3 + 1, then G contains a r...

Recently, Bacsó and Tuza gave a full characterization of the graphs for which every connected induced subgraph has a connected dominating subgraph satisfying an arbitrary prescribed hereditary property. Using their result, we derive a similar characterization of the graphs for which any isolate-free induced subgraph has a total dominating subgraph that satisfies a prescribed additive hereditary...

An edge dominating set in a graph G is a set of edges D such that every edge not in D is adjacent to an edge of D. An edge domatic partition of a graph C=(V, E) is a collection of pairwise-disjoint edge dominating sets of G whose union is E. The maximum size of an edge domatic partition of G is called the edge domatic number. In this paper, we study the edge domatic number of the complete parti...

Abstract. We propose a notion of extended dominating set whereby each node in an ad hoc network is covered by either a dominating neighbor or several 2-hop dominating neighbors. This work is motivated by cooperative communication in ad hoc networks where transmitting independent copies of a packet generates diversity and combats the effects of fading. In this paper we propose several efficient ...

The rainbow connection number of a graph G is the least number of colours in a (not necessarily proper) edge-colouring of G such that every two vertices are joined by a path which contains no colour twice. Improving a result of Caro et al., we prove that the rainbow connection number of every 2-connected graph with n vertices is at most dn/2e. The bound is optimal.

For any edge of an isolate free graph , , 〈 〉 is the subgraph induced by the vertices adjacent to u and v in G. We say that an edge x, edominates an edge y if ∈ 〈 〉 . A set ⊆ is an Edge-Edge Dominating Set (EED-set) if every edge in is e-dominated by an edge in L. The edgeedge domination number is the cardinality of a minimum EED-set. We find the relation ship between the new parameter and some...

Let G = (V; E) be a /nite and undirected graph without loops and multiple edges. An edge is said to dominate itself and any edge adjacent to it. A subset D of E is called a perfect edge dominating set if every edge of E \ D is dominated by exactly one edge in D and an e cient edge dominating set if every edge of E is dominated by exactly one edge in D. The perfect (e cient) edge domination prob...