proposition: Fact frac0q x : fracq (0, x) = zeroq.
proof: Proof. apply: val_inj; rewrite //= val_fracq/= div0n !gcd0n !mulr0 !divnn. by have [//|x_neq0] := eqVneq; rewrite absz_gt0 x_neq0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order ssralg countalg div ssrnum) mathcomp(ssrint prime archimedean)