const In : set set prop term iIn = In infix iIn 2000 2000 const Empty : set const real : set axiom real_0: Empty iIn real const CSNo_Im : set set const SNo_pair : set set set axiom complex_Im_eq: !x:set.x iIn real -> !y:set.y iIn real -> CSNo_Im (SNo_pair x y) = y axiom SNo_pair_0: !x:set.SNo_pair x Empty = x claim !x:set.x iIn real -> CSNo_Im x = Empty