English
The canonical map of α into FreeGroup α is injective.
Русский
Каноническое отображение α в FreeGroup α инъективно.
LaTeX
$$$\\text{of}: \\alpha \\to FreeGroup(\\alpha)$ is injective.$$
Lean4
/-- The canonical map from the type to the free group is an injection. -/
@[to_additive /-- The canonical map from the type to the additive free group is an injection. -/
]
theorem of_injective : Function.Injective (@of α) := fun _ _ H =>
by
let ⟨L₁, hx, hy⟩ := Red.exact.1 H
simp [Red.singleton_iff] at hx hy; simp_all