const SNo : set prop const mul_SNo : set set set term * = mul_SNo infix * 2291 2290 axiom SNo_mul_SNo: !x:set.!y:set.SNo x -> SNo y -> SNo (x * y) const In : set set prop term iIn = In infix iIn 2000 2000 const real : set lemma !x:set.!y:set.x iIn real -> y iIn real -> SNo x -> SNo y -> SNo (x * y) -> x * y iIn real var x:set var y:set hyp x iIn real hyp y iIn real hyp SNo x claim SNo y -> x * y iIn real