∀ {V₁ : Type u_2} {V₂ : Type u_4} [inst : SeminormedAddCommGroup V₁] [inst_1 : SeminormedAddCommGroup V₂]
  {W₁ : Type u_3} {W₂ : Type u_1} [inst_2 : SeminormedAddCommGroup W₁] [inst_3 : SeminormedAddCommGroup W₂]
  {f₁ g₁ : NormedAddGroupHom V₁ W₁} {f₂ g₂ : NormedAddGroupHom V₂ W₂} (φ : NormedAddGroupHom V₁ V₂)
  (ψ : NormedAddGroupHom W₁ W₂),
  ψ.comp f₁ = f₂.comp φ →
    ψ.comp g₁ = g₂.comp φ →
      f₂.comp (φ.comp (NormedAddGroupHom.Equalizer.ι f₁ g₁)) = g₂.comp (φ.comp (NormedAddGroupHom.Equalizer.ι f₁ g₁))