| m + 1 < # x, ∀ x0. m < # x0 → x0.first ' + firstn(m, x0.rest) = firstn(m, x0) + x0[m] ' ⊦ x = [], x.rest.first ' + firstn(m, x.rest.rest) = firstn(m, x.rest) + x.rest[m] ' |
x = a + y, m + 1 < # x, ∀ x0. m < # x0 → x0.first ' + firstn(m, x0.rest) = firstn(m, x0) + x0[m] ' ⊦ x = [], y.first ' + firstn(m, y.rest) = firstn(m, y) + y[m] '
Used simplifier rules: x ≠ [] ⊦ a = x.first ∧ y = x.rest ↔ x = a + y; (elim) Used terms: x, a, y