proposition: Lemma sqrtr1 : sqrt 1 = 1 :> R.
proof: Proof. by move: (sqrtr_sqr 1); rewrite expr1n => ->; rewrite normr1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)