On Friendly Index Sets of Cyclic Silicates

Abstract:

      Let $G$ be a graph with vertex set $V(G)$ and edge set $E(G)$. A labeling $f : V(G)\rightarrow Z_{2}$ induces an edge labeling $ f^{*} : E(G)\rightarrow Z_{2}$ defined by $f^{*}(xy) = f(x) + f(y)$, for each edge $ xy\in E(G)$. For $i \in Z_{2}$, let $ v_{f}(i) =|\{v \in V(G) : f(v) = i\}|$ and $e_{f}(i) = |\{e\in E(G) : f^{*}(e) = i\}|$. A labeling $f$ of a graph $G$ is said to be friendly if $| v_{f}(0)-v_{f}(1) | \leq 1$. The friendly index set of the graph $G$, denoted ${\rm FI}(G)$, is defined as $\{|e_{f}(0) - e_{f}(1)|$: the vertex labeling $f$ is friendly$\}$. This is a generalization of graph cordiality. We investigate the friendly index sets of cyclic silicates CS$(n, m)$.