English
The coalgebra structure on A × B is defined componentwise via coproduct maps.
Русский
Коалгебраическая структура на произведении A × B задаётся по компонентам через копроводящие карты.
LaTeX
$$$\\text{instCoalgebraStruct } R (A \\times B)$ with 1) comul = \\cdot, 2) counit = \\cdot$$$
Lean4
instance instCoalgebraStruct : CoalgebraStruct R (A × B)
where
comul :=
.coprod (TensorProduct.map (.inl R A B) (.inl R A B) ∘ₗ comul)
(TensorProduct.map (.inr R A B) (.inr R A B) ∘ₗ comul)
counit := .coprod counit counit