The power domination problem aims to find the minimum number of phase measurement units (PMUs) required in order to observe the entire electric power system. Zhao and Kang [6] remarked that there is no known nonplanar graph of diameter two with a power domination number that is arbitrarily large. In this note, we show that the power domination number of such graphs can be arbitrarily large.

Vizing’s conjecture from 1968 asserts that the domination number of the Cartesian product of two graphs is at least as large as the product of their domination numbers. In this note we use a new, transparent approach to prove Vizing’s conjecture for graphs with domination number 3; that is, we prove that for any graph G with γ(G) = 3 and an arbitrary graph H, γ(G H) > 3γ(H).

Let $kgeq 1$ be an integer, and let $G$ be a graph. A {it$k$-rainbow dominating function} (or a {it $k$-RDF}) of $G$ is afunction $f$ from the vertex set $V(G)$ to the family of all subsetsof ${1,2,ldots ,k}$ such that for every $vin V(G)$ with$f(v)=emptyset $, the condition $bigcup_{uinN_{G}(v)}f(u)={1,2,ldots,k}$ is fulfilled, where $N_{G}(v)$ isthe open neighborhood of $v$. The {it weight} o...

A dominating set of a graph G is a vertex subset that any vertex of G either belongs to or is adjacent to. A total dominating set is a dominating set whose induced subgraph does not contain isolated vertices. The minimal size of a total dominating set, the total domination number, is denoted by γt. The maximal size of an inclusionwise minimal total dominating set, the upper total domination num...

We present a counterexample to a lower bound for the power domination number given in Liao, Power domination with bounded time constraints, J. Comb. Optim. 31 (2016): 725–742. We also define the power propagation time, using the power domination propagation ideas in Liao and the (zero forcing) propagation time in Hogben et al, Propagation time for zero forcing on a graph, Discrete Appl. Math., ...

5 We present a counterexample to a lower bound for power domination number given in Liao, Power 6 domination with bounded time constraints, J. Comb. Optim., in press 2014. We also define the power 7 propagation time and make connections between the power domination propagation ideas in Liao and the 8 (zero forcing) propagation time in Hogben et al, Propagation time for zero forcing on a graph, ...

A graph G is an efficient open domination graph if there exists a subset D of V (G) for which the open neighborhoods centered in vertices of D form a partition of V (G). We completely describe efficient domination graphs among direct, lexicographic and strong products of graphs. For the Cartesian product we give a characterization when one factor is K2 and some partial results for grids, cylind...

The game domination number is a graph invariant that arises from a game, which is related to graph domination in a similar way as the game chromatic number is related to graph coloring. In this paper we show that verifying whether the game domination number of a graph is bounded by a given integer is PSPACEcomplete. This contrasts the situation of the game coloring problem whose complexity is s...

In this paper, we are concerned with the krainbow domination problem on generalized de Bruijn digraphs. We give an upper bound and a lower bound for the k-rainbow domination number in generalized de Bruijn digraphs GB(n, d). We also show that γrk(GB(n, d)) = k if and only if α 6 1, where n = d+α and γrk(GB(n, d)) is the k-rainbow domination number of GB(n, d).