const ordinal : set prop const SNo_ : set set prop term SNo = \x:set.?y:set.ordinal y & SNo_ y x const In : set set prop term iIn = In infix iIn 2000 2000 const SNoLt : set set prop term < = SNoLt infix < 2020 2020 term SNoCutP = \x:set.\y:set.(!z:set.z iIn x -> SNo z) & (!z:set.z iIn y -> SNo z) & !z:set.z iIn x -> !w:set.w iIn y -> z < w const Sep : set (set prop) set const SNoS_ : set set const SNoLev : set set term SNoL = \x:set.Sep (SNoS_ (SNoLev x)) \y:set.y < x term SNoR = \x:set.Sep (SNoS_ (SNoLev x)) (SNoLt x) var x:set var y:set var z:set hyp y < x hyp z iIn SNoLev x hyp SNo y hyp SNoLev y = z claim SNoLev y iIn SNoLev x -> SNo y & SNoLev y iIn SNoLev x & y < x