$\forall$${\it es}$:ES, $X$:AbsInterface(Top), $f$:(E($X$)$\rightarrow$E($X$)).
\\[0ex]($\forall$$x$:E($X$). $f$($x$) c$\leq$ $x$) $\Rightarrow$ ($\forall$$e$, ${\it e'}$:E($X$). (${\it e'}$ $\in$ prior{-}$f${-}fixedpoints($e$)) $\Rightarrow$ ($f$(${\it e'}$) = ${\it e'}$ $\in$ E))