| # y ≤ # x0, a ∈ a ' + x0 → (∃ y0, z. y = y0 + (a + z)), ∀ a0. a0 ∈ a ' + x0 → a0 ∈ y, ∀ y0. # y0 < # x0 ∧ (∀ a. a ∈ x0 → a ∈ y0) → x0 = [] ∨ dups(y0) ⊦ dups(y), dups(x0), a ∈ x0 |
# y0 + # z < # x0, ∀ a0. a0 ∈ x0 → a0 ∈ y0 ∨ a0 ∈ z, ∀ y. # y < # x0 ∧ (∀ a. a ∈ x0 → a ∈ y) → dups(y) ⊦ x0 = [], dups(y0 + z), dups(x0), a ∈ z, a ∈ y0, a ∈ x0
Used simplifier rules: f-01: ⊦ dups(x + a ' + y) ↔ a ∈ x ∨ a ∈ y ∨ dups(x + y);% ⊦ # x = 0 ↔ x = []; (s)%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic%c: ⊦ m + n = n + m; from specification nat-basic%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic% ⊦ m + 1 ≤ n ↔ m < n; (s)% ⊦ # a ' = 0 +1; (s)% ⊦ #(x + y) = # x + # y; (s)% ⊦ a + x = a ' + x; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a ∈ b ' ↔ a = b; (s)% ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s)