const In : set set prop term iIn = In infix iIn 2000 2000 const SNo : set prop 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 term Subq = \x:set.\y:set.!z:set.z iIn x -> z iIn y term TransSet = \x:set.!y:set.y iIn x -> Subq y x 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) term ordinal = \x:set.TransSet x & !y:set.y iIn x -> TransSet y const minus_SNo : set set term - = minus_SNo const Repl : set (set set) set var x:set var y:set hyp SNo x hyp !z:set.z iIn SNoS_ (SNoLev x) -> SNo - z & (!w:set.w iIn SNoL z -> - z < - w) & (!w:set.w iIn SNoR z -> - w < - z) & SNoCutP (Repl (SNoR z) minus_SNo) (Repl (SNoL z) minus_SNo) hyp SNo y hyp SNoLev y iIn SNoLev x claim y iIn SNoS_ (SNoLev x) -> SNo - y & (!z:set.z iIn SNoL y -> - y < - z) & !z:set.z iIn SNoR y -> - z < - y