English
The length of dropSlice i j l equals length(l) minus the minimum of j and (length(l) - i).
Русский
Длина dropSlice i j l равна длине l минус min(j, length(l) - i).
LaTeX
$$$\\mathrm{length}(\\mathrm{dropSlice}(i,j,l)) = |l| - \\min\\{j, |l| - i\\}$$$
Lean4
theorem dropSlice_eq (xs : List α) (n m : ℕ) : dropSlice n m xs = xs.take n ++ xs.drop (n + m) := by
induction n generalizing xs with cases xs with grind [dropSlice]