mathlib documentation

topology.​category.​Top.​open_nhds

topology.​category.​Top.​open_nhds

def topological_space.​open_nhds {X : Top} :
X.αType u

Equations
@[simp]
theorem topological_space.​open_nhds.​map_id_obj' {X : Top} (x : X) (U : set X) (p : is_open U) (q : (𝟙 X) x U, p⟩) :
(topological_space.open_nhds.map (𝟙 X) x).obj U, p⟩, q⟩ = U, p⟩, q⟩