English
In a product α × β with HasCompl on each component, the first projection of aᶜ equals the complement of the first projection: aᶜ₁ = (a₁)ᶜ.
Русский
В произведении α × β с/complement на каждой компоненте, первая проекция aᶜ равна комплементу первой проекции: aᶜ₁ = (a₁)ᶜ.
LaTeX
$$$ a^\complement_1 = a_1^\complement $$$
Lean4
@[simp]
theorem fst_compl [HasCompl α] [HasCompl β] (a : α × β) : aᶜ.1 = a.1ᶜ :=
rfl