English
A function f is locally injective if every point has a neighborhood on which f is injective.
Русский
Функция f локально инъективна, если для каждой точки найдется окрестность, на которой f инъективна.
LaTeX
$$def IsLocallyInjective (f : X → Y) : Prop := ∀ x : X, ∃ U, IsOpen U ∧ x ∈ U ∧ U.InjOn f$$
Lean4
/-- A function from a topological space `X` is locally injective if every point of `X`
has a neighborhood on which `f` is injective. -/
def IsLocallyInjective (f : X → Y) : Prop :=
∀ x : X, ∃ U, IsOpen U ∧ x ∈ U ∧ U.InjOn f