English
For a vector formed as a ::ᵥ v and i : Fin n, the (i+1)-th element equals the i-th element of v.
Русский
Для вектора a ::ᵥ v и i : Fin n, элемент с индексом i.succ равен элементу i в v.
LaTeX
$$$\\forall {\\alpha} {n} (a:\\alpha) (v:\\mathrm{Vector}\\ \\alpha\\ n) (i:\\mathrm{Fin} n),\\; \\mathrm{get}(\\mathrm{cons}(a,v), i.succ) = \\mathrm{get}(v,i)$$$
Lean4
@[simp]
theorem get_cons_succ (a : α) (v : Vector α n) (i : Fin n) : get (a ::ᵥ v) i.succ = get v i := by
rw [← get_tail_succ, tail_cons]