const In : set set prop term iIn = In infix iIn 2000 2000 term Subq = \x:set.\y:set.!z:set.z iIn x -> z iIn y const Power : set set axiom PowerE: !x:set.!y:set.y iIn Power x -> Subq y x const Repl : set (set set) set axiom ReplE_impred: !x:set.!f:set set.!y:set.y iIn Repl x f -> !P:prop.(!z:set.z iIn x -> y = f z -> P) -> P axiom PowerI: !x:set.!y:set.Subq y x -> y iIn Power x claim !x:set.!y:set.!f:set set.(!z:set.z iIn x -> f z iIn y) -> !z:set.z iIn Power x -> Repl z f iIn Power y