proposition: Lemma fposN f : fpos (- f) =1 fneg f.
proof: Proof. by move=> x; rewrite /fpos /fneg -{1}oppr0 -oppr_min normrN. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp) xfinmap ereal reals discrete realseq mathcomp.classical(classical_sets functions mathcomp_extra) topology