English
Casting the successor satisfies cast(succ n) = cast(n) + 1.
Русский
Преобразование преемника удовлетворяет cast(succ n) = cast(n) + 1.
LaTeX
$$$\\forall n \\in \\text{PosNum},\\; \\operatorname{castPosNum}(\\operatorname{succ} n) = \\operatorname{castPosNum}(n) + 1$$$
Lean4
@[simp 500, norm_cast]
theorem cast_succ [AddMonoidWithOne α] (n : PosNum) : (succ n : α) = n + 1 := by rw [← add_one, cast_add, cast_one]