`{!HasEquivs A} (be : b $<~> zero_object) : g $o f $== zero_morphism a c. Proof. refine (_ $@L (compose_V_hh be f)^$ $@ _). refine (cat_assoc_opp _ _ _ $@ _). refine (_ $@L (mor_terminal_unique a _ _)^$ $@ _). exact ((mor_initial_unique _ _ _)^$ $@R _). Defined.
Require Import Basics.Overture Basics.Tactics. Require Import WildCat.Core WildCat.Opposite. Require Import WildCat.Equiv.