fact: Definition equiv_sequence (D1 D2 : Sequence) (H0 : (D1 0) <~> (D2 0)) (Hn: forall n (e: (D1 n) <~> (D2 n)), {e' : (D1 n.+1) <~> (D2 n.+1) & (D2 _f 1) o e == e' o (D1 _f 1)}) : D1 ~d~ D2.
imports: Basics Diagrams.Graph Diagrams.Diagram