English
The upper topology on a product is obtained by dualizing the lower-product construction.
Русский
Верхняя топология на произведении получаются путем дуализации конструирования нижней топологии на произведении.
LaTeX
$$$IsUpper(\alpha \times \beta)$$$
Lean4
instance instIsUpperProd [Preorder α] [TopologicalSpace α] [IsUpper α] [OrderTop α] [Preorder β] [TopologicalSpace β]
[IsUpper β] [OrderTop β] : IsUpper (α × β) where
topology_eq_upperTopology :=
by
suffices IsLower (α × β)ᵒᵈ from IsLower.topology_eq_lowerTopology (α := (α × β)ᵒᵈ)
exact instIsLowerProd (α := αᵒᵈ) (β := βᵒᵈ)