English
If m is the index type and the ring α has 1, then blockDiagonal of the constant identity blocks is the identity.
Русский
Если размерность блочной диагонали равна m и над тёзм α имеется единица, то блочная диагональ единичных блоков равна единице.
LaTeX
$$$\operatorname{blockDiagonal}(1) = 1.$$$
Lean4
@[simp]
theorem blockDiagonal_one [DecidableEq m] [One α] : blockDiagonal (1 : o → Matrix m m α) = 1 :=
show (blockDiagonal fun _ : o => diagonal fun _ : m => (1 : α)) = diagonal fun _ => 1 by rw [blockDiagonal_diagonal]