const In : set set prop term iIn = In infix iIn 2000 2000 const omega : set const nat_p : set prop axiom omega_nat_p: !x:set.x iIn omega -> nat_p x const SNo : set prop const ordinal : set prop const add_nat : set set set const add_SNo : set set set term + = add_SNo infix + 2281 2280 var x:set hyp ordinal x hyp SNo x claim (!y:set.nat_p y -> add_nat x y = x + y) -> !y:set.y iIn omega -> add_nat x y = x + y