English
If R is an equivalence, then LiftRel R is an equivalence on weak sequences.
Русский
Если R — эквивалентность, то LiftRel R — эквивалентность на слабых последовательностях.
LaTeX
$$$$ (R\text{ is Equivalence}) \Rightarrow \mathrm{Equivalence}(\mathrm{LiftRel}\ R). $$$$
Lean4
theorem equiv (R : α → α → Prop) : Equivalence R → Equivalence (LiftRel R)
| ⟨refl, symm, trans⟩ => ⟨LiftRel.refl R refl, @(LiftRel.symm R @symm), @(LiftRel.trans R @trans)⟩