English
Let X be a topological space, r a relation, and f: X → Y a map constant on r-equivalence classes. Then the lift to the quotient Quot r → Y is continuous.
Русский
Пусть X — топологическое пространство, r — эквивалентность, и f: X → Y such that f(a) = f(b) whenever a ~ b. Тогда отображение Quotient r → Y, заданное подъемом, непрерывно.
LaTeX
$$$$ \mathrm{Continuous}(\operatorname{Quotient\_lift}(f, hr)) $$$$
Lean4
@[continuity, fun_prop]
theorem continuous_quot_lift {f : X → Y} (hr : ∀ a b, r a b → f a = f b) (h : Continuous f) :
Continuous (Quot.lift f hr : Quot r → Y) :=
continuous_coinduced_dom.2 h