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Added a couple of simp lemmas
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Nicknamen committed Mar 20, 2021
1 parent 41a17c7 commit eaef82e
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22 changes: 22 additions & 0 deletions src/topology/vector_bundle.lean
Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,19 @@ structure topological_vector_bundle.trivialization extends bundle_trivialization
instance : has_coe_to_fun (topological_vector_bundle.trivialization 𝕜 F E) :=
⟨λ _, (total_space E → B × F), λ e, e.to_bundle_trivialization⟩

instance : has_coe (topological_vector_bundle.trivialization 𝕜 F E)
(bundle_trivialization F (proj E)) :=
⟨topological_vector_bundle.trivialization.to_bundle_trivialization⟩

namespace topological_vector_bundle

variables {𝕜 F E}

lemma trivialization.mem_source (e : trivialization 𝕜 F E)
{x : total_space E} : x ∈ e.source ↔ proj E x ∈ e.base_set := bundle_trivialization.mem_source e

end topological_vector_bundle

end

variables [∀ x, topological_space (E x)]
Expand Down Expand Up @@ -101,6 +114,8 @@ classical.some_spec (topological_vector_bundle.locally_trivial 𝕜 F E b)
z ∈ (trivialization_at 𝕜 F E z.1).source :=
by { rw bundle_trivialization.mem_source, apply mem_base_set_trivialization_at }

variables {𝕜 F E}

/-- In a topological vector bundle, a trivialization in the fiber (which is a priori only linear)
is in fact a continuous linear equiv between the fibers and the model fiber. -/
def trivialization.continuous_linear_equiv_at (e : trivialization 𝕜 F E) (b : B)
Expand Down Expand Up @@ -163,6 +178,13 @@ def trivialization.continuous_linear_equiv_at (e : trivialization 𝕜 F E) (b :
{ exact cast_heq _ _ },
end }

@[simp] lemma trivialization.continuous_linear_equiv_at_apply (e : trivialization 𝕜 F E) (b : B)
(hb : b ∈ e.base_set) (y : E b) : e.continuous_linear_equiv_at b hb y = (e ⟨b, y⟩).2 := rfl

@[simp] lemma trivialization.continuous_linear_equiv_at_apply' (e : trivialization 𝕜 F E)
(x : total_space E) (hx : x ∈ e.source) :
e.continuous_linear_equiv_at (proj E x) (e.mem_source.1 hx) x.2 = (e x).2 :=
by { cases x, refl }

section
local attribute [reducible] bundle.trivial
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