const SNo : set prop const mul_SNo : set set set term * = mul_SNo infix * 2291 2290 axiom mul_SNo_com: !x:set.!y:set.SNo x -> SNo y -> x * y = y * x axiom mul_SNo_assoc: !x:set.!y:set.!z:set.SNo x -> SNo y -> SNo z -> x * y * z = (x * y) * z claim !x:set.!y:set.!z:set.SNo x -> SNo y -> SNo z -> (x * y) * z = (x * z) * y