English
The inclusion map of Permutation on the subtype into Perm α is injective.
Русский
Включение перестановок подтипа в перестановки α инъективно.
LaTeX
$$$ \\text{Injective}(\\mathrm{ofSubtype} : \\operatorname{Perm}(\\operatorname{Subtype} p) \\to \\operatorname{Perm}(\\alpha)) $$$
Lean4
theorem ofSubtype_injective : Function.Injective (ofSubtype : Perm (Subtype p) → Perm α) :=
by
intro x y h
rw [Perm.ext_iff] at h ⊢
intro a
specialize h a
rwa [ofSubtype_apply_coe, ofSubtype_apply_coe, SetCoe.ext_iff] at h