$\forall$$T$:Type, $P$:($T$$\rightarrow$Prop), $R$:($T$$\rightarrow$$T$$\rightarrow$Prop).
\\[0ex](Sym $x$,$y$:$T$. $x$ $R$ $y$) $\Rightarrow$ $R$ preserves $P$ $\Rightarrow$ $R$$^{\mbox{\scriptsize {-}1}}$ preserves $P$