proposition: Lemma pihalf_ge1 : 1 <= pi / 2.
proof: Proof. by have /andP[] := pihalf_12. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) reals ereal nsatz_realtype signed topology normedtype landau sequences derive realfun exp