const Subq : set set prop const Sep : set (set prop) set axiom Sep_Subq: !x:set.!p:set prop.Subq (Sep x p) x const In : set set prop term iIn = In infix iIn 2000 2000 const Power : set set axiom PowerI: !x:set.!y:set.Subq y x -> y iIn Power x claim !x:set.!p:set prop.Sep x p iIn Power x