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$\forall$$g$:IMonoid, $a$, $b$, $c$:$\mathbb{Z}$.
\\[0ex]($a$ $\leq$ $b$)
\\[0ex]$\Rightarrow$ ($b$ $<$ $c$)
\\[0ex]$\Rightarrow$ \=($\forall$$E$:(\{$a$..$c$$^{-}$\}$\rightarrow\mid$$g$$\mid$).\+
\\[0ex]($\Pi$ $a$ $\leq$ $j$ $<$ $c$. $E$($j$)) = (($\Pi$ $a$ $\leq$ $j$ $<$ $b$. $E$($j$)) $\ast$ ($E$($b$) $\ast$ ($\Pi$ $b$+1 $\leq$ $j$ $<$ $c$. $E$($j$)))) $\in$ $\mid$$g$$\mid$)
\-
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