| n + m ≤ # x ⊦ x from m from n = x from m + n |
∀ n, m. n + m ≤ # x0 → x0 from m from n = x0 from m + n, n + m ≤ #(a + x0) ⊦ a + x0 from m from n = a + x0 from m + n
Used simplifier rules: from-zero-l: ⊦ x from 0 = x;%list freely generated by [], +;;%size-01: ⊦ # [] = 0; from specification list-data%lez-01: ⊦ m ≤ 0 ↔ m = 0; from specification nat%z-01: ⊦ m + n = 0 ↔ m = 0 ∧ n = 0; from specification nat-basic2%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic2%c: ⊦ m + n = n + m; from specification nat-basic2