$\forall$$T$:Type, $R$:($T$$\rightarrow$$T$$\rightarrow$Prop), $x$, $y$:$T$. ($x$ $R$\^{}+ $y$) $\Rightarrow$ ($x$ $R$ $y$) $\vee$ ($\exists$$z$:$T$. ($x$ $R$\^{}+ $z$) \& ($z$ $R$ $y$))