| ⊦ perm(x + y, z + y) ↔ perm(x, z) |
∀ a. #oc(a, x) ≤ #oc(a, z), ∀ a. #oc(a, z) ≤ #oc(a, x) ⊦ #oc(a, x) ≤ #oc(a, z) ∧ #oc(a0, z) ≤ #oc(a0, x)
Used simplifier rules: perm-def: ⊦ perm(x, y) ↔ ¬ ¬(x ⊆m y ∧ y ⊆m x);%msubset: ⊦ x ⊆m y ↔ (∀ a. #oc(a, x) ≤ #oc(a, y));%ocappend: ⊦ #oc(a, x + y) = #oc(a, x) + #oc(a, y);%c: ⊦ m + n = n + m; from specification nat-basic2%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic2%lep-02: ⊦ m + n ≤ m + n0 ↔ n ≤ n0; from specification nat%a: ⊦ (x + y) + z = x + y + z; from specification list