∀ {B : Type u_2} {F : Type u_3} {Z : Type u_1} [inst : TopologicalSpace B] [inst_1 : TopologicalSpace F] {proj : Z → B}
  [inst_2 : TopologicalSpace Z] (e e' : Bundle.Trivialization F proj) (s : Set B),
  e.baseSet ∩ frontier s = e'.baseSet ∩ frontier s →
    e.source ∩ frontier (proj ⁻¹' s) = e'.source ∩ frontier (proj ⁻¹' s)