fact: Fixpoint T1_T3 (c:CantorOrdinal.T1) : T3 := if c is CantorOrdinal.cons a n b then cons zero zero (T1_T3 a) n (T1_T3 b) else zero.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(fintype bigop)