fact: Definition common_extension_order_axiom g := [/\ order_fam g, (forall a b, inc a (domain g) -> inc b (domain g )-> exists c, [/\ inc c (domain g), sub (substrate (Vg g a)) (substrate (Vg g c)) & sub (substrate (Vg g b)) (substrate (Vg g c))]) & monotone_order_fam g].
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)