English
Let h be InjOn g s and hs range f ⊆ s. Then Injective (g ∘ f) iff Injective f.
Русский
Пусть h — InjOn g s и hs: range f ⊆ s. Тогда Injective (g ∘ f) эквивалентно Injective f.
LaTeX
$$$ [\\operatorname{InjOn} g s] (\\operatorname{range} f \\subseteq s) \\Rightarrow (\\operatorname{Injective}(g \\circ f) \\iff \\operatorname{Injective}(f))$$$
Lean4
theorem _root_.Set.InjOn.injective_iff (s : Set β) (h : InjOn g s) (hs : range f ⊆ s) :
Injective (g ∘ f) ↔ Injective f :=
⟨(·.of_comp), fun h _ ↦ by aesop⟩