∀ {B : Type u_1} {F₁ : Type u_2} [inst : NormedAddCommGroup F₁] {E₁ : B → Type u_3}
  [inst_1 : TopologicalSpace (Bundle.TotalSpace F₁ E₁)] {F₂ : Type u_4} [inst_2 : NormedAddCommGroup F₂]
  {E₂ : B → Type u_5} [inst_3 : TopologicalSpace (Bundle.TotalSpace F₂ E₂)] [inst_4 : TopologicalSpace B]
  (e₁ : Trivialization F₁ Bundle.TotalSpace.proj) (e₂ : Trivialization F₂ Bundle.TotalSpace.proj),
  IsOpen (e₁.baseSet ∩ e₂.baseSet)