fact: Record mixin_of := Mixin { mx_sup : Pred T -> T; _ : forall (s : Pred T) x, x \In s -> x <== mx_sup s; _ : forall (s : Pred T) x, (forall y, y \In s -> y <== x) -> mx_sup s <== x}.
imports: mathcomp(ssreflect ssrbool ssrfun ssrnat eqtype seq) pcm(options axioms pred prelude)