| ∀ x, a. (perm(x, mklist(a, #oc(a, x)) + y0) ↔ perm(x -l a, y0)) ∨ a ∈ y0 ⊦ perm(x, mklist(a, #oc(a, x)) + (a0 + y0)) ↔ perm(x -l a, a0 + y0), a ∈ a0 + y0 |
∀ x, a. (perm(x, mklist(a, #oc(a, x)) + y0) ↔ perm(x -l a, y0)) ∨ a ∈ y0 ⊦ perm(x, mklist(a, #oc(a, x)) + a0 ' + y0) ↔ a0 ∈ x ∧ perm((x -l a) -1l a0, y0), a = a0, a ∈ y0
Used simplifier rules: del: ⊦ perm(x, a ' + y) ↔ a ∈ x ∧ perm(x -1l a, y);% ⊦ a ∈ x -l b ↔ a ∈ x ∧ a ≠ b; (ws)% ⊦ a ∈ b ' + x ↔ ¬(a ≠ b ∧ ¬ a ∈ x); (ss)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a + x = a ' + x; (s)