case intro
B : Type u_1
F : Type u_2
Z : Type u_3
inst✝² : TopologicalSpace B
inst✝¹ : TopologicalSpace F
inst✝ : TopologicalSpace Z
e : Z ≃ₜ B × F
h : IsHomeomorphicTrivialFiberBundle F (Prod.fst ∘ ↑e)
⊢ IsOpenMap (Prod.fst ∘ ↑e)
B : Type u_1
F : Type u_2
Z : Type u_3
inst✝² : TopologicalSpace B
inst✝¹ : TopologicalSpace F
inst✝ : TopologicalSpace Z
proj : Z → B
h : IsHomeomorphicTrivialFiberBundle F proj
⊢ IsOpenMap proj
obtain ⟨e, rfl⟩ := h.proj_eq
no goals
case intro
B : Type u_1
F : Type u_2
Z : Type u_3
inst✝² : TopologicalSpace B
inst✝¹ : TopologicalSpace F
inst✝ : TopologicalSpace Z
e : Z ≃ₜ B × F
h : IsHomeomorphicTrivialFiberBundle F (Prod.fst ∘ ↑e)
⊢ IsOpenMap (Prod.fst ∘ ↑e)
exact isOpenMap_fst.comp e.isOpenMap