\begin{tabbing} $\vdash$ \=$\forall$$T$:Type, $R$:($T$$\rightarrow$$T$$\rightarrow\mathbb{P}$).\+ \\[0ex]Trans($T$;$x$,$y$.$R$($x$,$y$)) \\[0ex]$\Rightarrow$ \=\{$\forall$$a$, ${\it a'}$, $b$, ${\it b'}$:$T$.\+ \\[0ex]Symmetrize($x$,$y$.$R$($x$,$y$);$a$;$b$) $\Rightarrow$ Symmetrize($x$,$y$.$R$($x$,$y$);${\it a'}$;${\it b'}$) $\Rightarrow$ ($R$($a$,${\it a'}$) $\Leftarrow\!\Rightarrow$ $R$($b$,${\it b'}$))\} \-\- \end{tabbing}