const In : set set prop term iIn = In infix iIn 2000 2000 const SNoLev : set set const ordinal : set prop const SNo : set prop const SNo_ : set set prop lemma !x:set.!y:set.!P:prop.!z:set.(SNoLev y iIn x -> ordinal (SNoLev y) -> SNo y -> SNo_ (SNoLev y) y -> P) -> z iIn x -> SNo y -> ordinal (SNoLev y) -> SNo_ (SNoLev y) y -> SNoLev y = z -> SNoLev y iIn x -> P var x:set var y:set var P:prop var z:set hyp SNoLev y iIn x -> ordinal (SNoLev y) -> SNo y -> SNo_ (SNoLev y) y -> P hyp z iIn x hyp SNo_ z y hyp ordinal z hyp SNo y hyp ordinal (SNoLev y) hyp SNo_ (SNoLev y) y claim SNoLev y = z -> P