English
Operator ite acts componentwise: ite P A B i j = ite P (A i j) (B i j).
Русский
Оператор ite действует по элементам: ite P A B i j = ite P (A i j) (B i j).
LaTeX
$$$ \forall P\; [Decidable P],\ A,B : Matrix m n \alpha,\ i : m,\ j : n,\ ite P A B i j = ite P (A i j) (B i j)$$$
Lean4
protected theorem ite_apply (P : Prop) [Decidable P] (A : Matrix m n α) (B : Matrix m n α) (i : m) (j : n) :
(if P then A else B) i j = if P then A i j else B i j :=
Matrix.dite_apply _ _ _ _ _