English
The coercion commutes with a bidirectional supremum: the coe of a nested iSup equals the nested iSup of coerced values.
Русский
Коэффициент совпадает с двойным сверху: коe(⋁ i, ⋁ (p i), f i) = ⋁ i, ⋁ (p i), (f i).
LaTeX
$$$$ \uparrow\Big(\operatorname{biSup}_{i} \operatorname{biSup}_{p(i)} f(i)\Big) = \operatorname{biSup}_{i} \operatorname{biSup}_{p(i)} (f(i) : α). $$$$
Lean4
theorem coe_biSup : (↑(⨆ i, ⨆ (_ : p i), f i) : α) = ⨆ i, ⨆ (_ : p i), (f i : α) := by simp