| n ≠ 0 ⊦ sublist(0, n, a ' + x) = a ' + sublist(0, n -1, x) |
⊦ n = 0, firstn(n, a ' + x) = a ' + firstn(n - 1, x)
Used simplifier rules: sublist-def: ⊦ sublist(m, n, x) = firstn(n, restn(m, x));%restN-zero: ⊦ restn(0, x) = x;%pred-03: ⊦ n -1 = n - 1; from specification nat