For an integer k ≥ 1 and a graph G = (V,E), a set S of V is k-independent if ∆(S) < k and k-dominating if every vertex in V \S has at least k neighbors in S. The k-independence number βk(G) is the maximum cardinality of a k-independent set and the k-dominating number is the minimum cardinality of a k-dominating set of G. Since every kindependent set is (k + 1)-independent and every (k + 1)-domi...

Given a graph G, a dominating set D is a set of vertices such that any vertex in G has at least one neighbor (or possibly itself) in D. A {k}-dominating multiset Dk is a multiset of vertices such that any vertex in G has at least k vertices from its closed neighborhood in Dk when counted with multiplicity. In this paper, we utilize the approach developed by Clark and Suen (2000) and properties ...

‎A Roman dominating function (RDF) on a graph G=(V,E) is a function  f : V → {0, 1, 2}  such that every vertex u for which f(u)=0 is‎ ‎adjacent to at least one vertex v for which f(v)=2‎. ‎An RDF f is called‎‎an outer independent Roman dominating function (OIRDF) if the set of‎‎vertices assigned a 0 under f is an independent set‎. ‎The weight of an‎‎OIRDF is the sum of its function values over ...

Given a graph G and a subgraph H of G, let rb(G,H) be the minimum number r for which any edge-coloring of G with r colors has a rainbow subgraph H. The number rb(G,H) is called the rainbow number of H with respect to G. Denote mK2 a matching of size m and Bn,k a k-regular bipartite graph with bipartition (X,Y ) such that |X| = |Y | = n and k ≤ n. In this paper we give an upper and lower bound f...

Let HPn,m,k be drawn uniformly from all m-edge, k-uniform, k-partite hypergraphs where each part of the partition is a disjoint copy of [n]. We let HP (κ) n,m,k be an edge colored version, where we color each edge randomly from one of κ colors. We show that if κ = n and m = Kn log n where K is sufficiently large then w.h.p. there is a rainbow colored perfect matching. I.e. a perfect matching in...

A path in a vertex-colored graph G is vertex rainbow if all of its internal vertices have a distinct color. The graph G is said to be rainbow vertex connected if there is a vertex rainbow path between every pair of its vertices. Similarly, the graph G is strongly rainbow vertex connected if there is a shortest path which is vertex rainbow between every pair of its vertices. We consider the comp...

We present an algorithm that constructively produces a solution to the k-dominating set problem for planar graphs in time O(c √ n), where c = 36 √ 34. To obtain this result, we show that the treewidth of a planar graph with domination number γ(G) is O( √ γ(G)), and that such a tree decomposition can be found in O( √ γ(G)n) time. The same technique can be used to show that the k-face cover probl...

A rainbow subgraph of an edge-coloured graph is a subgraph whose edges have distinct colours. The colour degree of a vertex v is the number of different colours on edges incident with v. Wang and Li conjectured that for k 4, every edge-coloured graph with minimum colour degree k contains a rainbow matching of size at least k/2 . A properly edge-coloured K4 has no such matching, which motivates ...

Given two graphs G and H, let f(G,H) denote the maximum number c for which there is a way to color the edges of G with c colors such that every subgraph H of G has at least two edges of the same color. Equivalently, any edge-coloring of G with at least rb(G,H) = f(G,H) + 1 colors contains a rainbow copy of H, where a rainbow subgraph of an edge-colored graph is such that no two edges of it have...