$\forall$$A$:Type, ${\it eq}_{1}$, ${\it eq}_{2}$:EqDecider($A$), $f$:$a$:$A$ fp$\rightarrow$ Top, $x$:$A$. \{$x$ $\in$ dom($f$) $\Rightarrow$ $x$ $\in$ dom($f$)\}