const Repl : set (set set) set const Sep : set (set prop) set term ReplSep = \x:set.\p:set prop.Repl (Sep x p) const In : set set prop term iIn = In infix iIn 2000 2000 axiom SepE: !x:set.!p:set prop.!y:set.y iIn Sep x p -> y iIn x & p y axiom ReplE: !x:set.!f:set set.!y:set.y iIn Repl x f -> ?z:set.z iIn x & y = f z claim !x:set.!p:set prop.!f:set set.!y:set.y iIn ReplSep x p f -> ?z:set.z iIn x & p z & y = f z