| m < # y, ∀ x0. m < # x0 → x0.first ' + firstn(m, x0.rest) = firstn(m, x0) + x0[m] ' ⊦ y.first ' + firstn(m, y.rest) = firstn(m, y) + y[m] ', y = [] |
y = a + y0, m < # y, ∀ x0. m < # x0 → x0.first ' + firstn(m, x0.rest) = firstn(m, x0) + x0[m] ' ⊦ a ' + firstn(m, y0) = firstn(m, y) + y[m] ', y = []
Used simplifier rules: x ≠ [] ⊦ a = x.first ∧ y = x.rest ↔ x = a + y; (elim) Used terms: y, a, y0