| n = n1 +1, n < m, n < pos(a, a0 ' + x0), a ∈ firstn(n, a0 ' + x0), m ≤ pos(a, a0 ' + x0), ∀ n0, m0, a1. ¬ n0 < m0 ∨ ¬ n0 < pos(a1, x0) ∨ ¬ a1 ∈ firstn(n0, x0) ∨ ¬ m0 ≤ pos(a1, x0) ⊦ |
n1 + 1 < m, n1 < pos(a, x0), a ∈ firstn(n1, x0), m ≤ pos(a, x0) + 1, ∀ n0, m0, a1. ¬ n0 < m0 ∨ ¬ n0 < pos(a1, x0) ∨ ¬ a1 ∈ firstn(n0, x0) ∨ ¬ m0 ≤ pos(a1, x0) ⊦ a = a0
Used simplifier rules: f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic% ⊦ m + n < m + n0 ↔ n < n0; (s)% ⊦ a ≠ b → pos(a, b ' + x) = pos(a, x) + 1; (s)% ⊦ m < n → n ≠ 0; (s)% ⊦ m ≤ 0 ↔ m = 0; (s)% ⊦ pos(a, a ' + x) = 0; (s)%fle: ⊦ m < n ∧ n ≤ n0 → m < n0; (forward) from specification nat% ⊦ a ∈ b ' + x ↔ a = b ∨ a ∈ x; (s)%c: ⊦ m + n = n + m; from specification nat-basic%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a + x = a ' + x; (s)% ⊦ firstn(n + 1, a ' + x) = a + firstn(n, x); (s)% ⊦ m +1 = m + 1; (s)