English
In a ordered commutative group G, the inverse of the atTop filter is the atBot filter: (atTop)^{-1} = atBot.
Русский
В упорядоченной абелевой группе G обратный фильтр к atTop равен фильтру atBot: (atTop)^{-1} = atBot.
LaTeX
$$$$ (atTop : Filter\, G)^{-1} = atBot. $$$$
Lean4
@[to_additive (attr := simp)]
theorem inv_atTop {G : Type*} [CommGroup G] [PartialOrder G] [IsOrderedMonoid G] : (atTop : Filter G)⁻¹ = atBot :=
(OrderIso.inv G).map_atTop