English
The right regular action of a group on itself is transitive: for any x,y ∈ G there exists g ∈ G with x•g = y (namely g = x⁻¹ y in opposite action).
Русский
Правое регулярное действие группы на самой группе транспитивно: для любых x,y ∈ G существует g ∈ G такое, что x·g = y.
LaTeX
$$$\\exists g \\in G, x \\cdot g = y$ for all x,y ∈ G; explicitly, take $g = x^{-1} y$ in the opposite action.$$
Lean4
/-- The right regular action of a group on itself is transitive. -/
@[to_additive /-- The right regular action of an additive group on itself is transitive. -/
]
instance isPretransitive_mulOpposite [Group G] : IsPretransitive Gᵐᵒᵖ G :=
⟨fun x y ↦ ⟨.op (x⁻¹ * y), mul_inv_cancel_left _ _⟩⟩