English
If 0 < length(l), then (scanr f b l).tail = scanr f b l.tail.
Русский
Если 0 < длина(l), то (scanr f b l).tail = scanr f b l.tail.
LaTeX
$$$$\forall l:\mathrm{List}(\alpha),\ 0 < \operatorname{length}(l) \Rightarrow (\operatorname{scanr} f b l).tail = (\operatorname{scanr} f b l.tail).$$$$
Lean4
theorem tail_scanr (h : 0 < l.length) : (scanr f b l).tail = scanr f b l.tail := by induction l <;> simp_all