English
For any a,b and domains ha,hb, a.get ha = b.get hb iff a = b.
Русский
Для любых a,b и доменов ha,hb: a.get ha = b.get hb эквивалентно a = b.
LaTeX
$$$$\forall a,b:\mathrm{Part}\,\alpha, ha:\mathrm{Dom}(a), hb:\mathrm{Dom}(b), a.get ha = b.get hb \iff a = b.$$$$
Lean4
theorem eq_iff_of_dom {a b : Part α} (ha : a.Dom) (hb : b.Dom) : a.get ha = b.get hb ↔ a = b :=
⟨eq_of_get_eq_get ha hb, get_eq_get_of_eq a ha⟩