| n0 + # y = m + 1, ∀ y0, n0, x. # y0 < # y → true → lastn(n0 + # y0, x + y0) = lastn(n0, x) + y0 ⊦ lastn(m, (x + y).butlast) + (x + y).last ' = lastn(n0, x) + y |
y = [], n0 + # y = m + 1, ∀ y0, n0, x. # y0 < # y → true → lastn(n0 + # y0, x + y0) = lastn(n0, x) + y0 ⊦ lastn(m, (x + y).butlast) + (x + y).last ' = lastn(n0, x) + y
n0 + # y = m + 1, ∀ y0, n0, x. # y0 < # y → true → lastn(n0 + # y0, x + y0) = lastn(n0, x) + y0 ⊦ y = [], lastn(m, (x + y).butlast) + (x + y).last ' = lastn(n0, x) + y
Used formulas: y = []