$\forall$$g$:IMonoid, $p$, $q$:$\mathbb{Z}$, $E$:(\{$p$..$q$$^{-}$\}$\rightarrow\mid$$g$$\mid$). ($\Pi$ $p$ $\leq$ $i$ $<$ $q$. $E$($i$)) $\in$ $\mid$$g$$\mid$