Locating-Dominating Sets of Functigraphs

A locating-dominating set of a graph $G$ is a dominating set of $G$ such that every vertex of $G$ outside the dominating set is uniquely identified by its neighborhood within the dominating set. The location-domination number of $G$ is the minimum cardinality of a locating-dominating set in $G$. Let $G_1$ and $G_2$ be the disjoint copies of a graph $G$ and $f:V(G_{1})\rightarrow V(G_{2})$beafunction\mathrm{.}Afunctigraph$F^f_{G}$consistsofthevertexset$V(G_{1})\cup V(G_{2})$andtheedgeset$E(G_{1})\cup E(G_{2})\cup {uv:v=f(u)}$. In this paper, we study the variation of the location-domination number in passing from $G$ to $F_G^f$ and find its sharp lower and upper bounds. We also study the location-domination number of functigraphs of the complete graphs for all possible definitions of the function $f$. We also obtain the location-domination number of functigraphs of a family of spanning subgraph of the complete graphs.