$k$-Fair Coalitions in Graphs

Let $G = (V,E)$ be a simple graph. A subset $S \subseteq V$ is called a $k$-fair dominating set if every vertex not in $S$ has exactly $k$ neighbors in $S$. Two disjoint sets $A, B \subseteq V$ form a $k$-fair coalition of $G$ if neither $A$ nor $B$ is a $k$-fair dominating set and the union $A \cup B$ is a $k$-fair dominating set of $G$. A partition $\pi = \{V_1, V_2, \ldots, V_m\}$ of $V$ is called a $k$-fair coalition partition, if every set $V_i\in\pi$, either $V_i$ is a $k$-fair dominating set with exactly $k$ vertices, or $V_i$ is not a $k$-fair dominating set, but forms a $k$-fair coalition with some other set $V_j$ in $\pi$. The $k$-fair coalition number $C_{kf}(G)$ is the largest possible size of a $k$-fair coalition partition for $G$. The objective of this study is to initiate an examination into the notion of $k$-fair coalitions in graphs and present essential findings.