\begin{tabbing}
$\forall$\=$E$,$X_{1}$,$X_{2}$:Type, ${\it dE}$:EqDecider($E$), ${\it dL}$:EqDecider(IdLnk), ${\it info}$:($E$$\rightarrow$(\=(:Id $\times$ $X_{1}$) + (:(:IdLnk $\times$ $E$)\+\+
\\[0ex]$\times$ $X_{2}$))),
\-\\[0ex]$e$,$r$:$E$, $l$:IdLnk. rcv{-}from{-}on(${\it dE}$; ${\it dL}$; ${\it info}$; $e$; $l$; $r$) $\in$ $\mathbb{B}$
\-
\end{tabbing}