English
For i ∈ Fin(n) and n ≠ 0, cycleIcc(0,i) equals cycleRange(i).
Русский
Для i ∈ Fin(n) и n ≠ 0, cycleIcc(0,i) равно cycleRange(i).
LaTeX
$$$\\forall {n : \\mathbb{N}} \\; \\forall {i : \\mathrm{Fin}(n)},\\; n \\neq 0 \\Rightarrow \\mathrm{cycleIcc}(0,i) = \\mathrm{cycleRange}(i)$$$
Lean4
theorem cycleIcc_zero_eq_cycleRange (i : Fin n) [NeZero n] : cycleIcc 0 i = cycleRange i :=
by
ext x
rcases lt_trichotomy x i with ch | ch | ch
· simp [-cycleIcc_def_le, cycleIcc_of_ge_of_lt (zero_le x) ch, cycleRange_of_lt ch]
· simp [-cycleIcc_def_le, ch]
· simp [-cycleIcc_def_le, cycleIcc_of_gt ch, cycleRange_of_gt ch]