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$\vdash$  \=$\forall$$T$:Type, $R$:($T$$\rightarrow$$T$$\rightarrow\mathbb{P}$).\+
\\[0ex]Preorder($T$;$x$,$y$.$R$($x$,$y$)) $\Rightarrow$ EquivRel($T$;$a$,$b$.Symmetrize($x$,$y$.$R$($x$,$y$);$a$;$b$))
\-
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