const ordinal : set prop const SNo : set prop const In : set set prop term iIn = In infix iIn 2000 2000 const SNoLev : set set const SNoLt : set set prop term < = SNoLt infix < 2020 2020 axiom ordinal_SNoLev_max: !x:set.ordinal x -> !y:set.SNo y -> SNoLev y iIn x -> y < x var x:set var y:set hyp ordinal x hyp y iIn x hyp ordinal y hyp SNo y claim SNoLev y = y -> y < x