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