Negate (Quotient fraction_eq). Proof. srapply Quotient_rec. - intros f. apply class_of. exact (frac_negate f). - intros f1 f2 p. by apply qglue, frac_negate_wd. Defined.
Require Import Basics.Overture Basics.Trunc Basics.Tactics Colimits.Quotient