| a ∈ x ∨ a ∈ y, a ∈ x ∨ a ∈ y → #oc(a, x) = #oc(a, y), ∀ a. a ∈ x ∨ a ∈ y → #oc(a, x) = #oc(a, y) ⊦ #oc(a, x) ≤ #oc(a, y) ∧ #oc(a0, y) ≤ #oc(a0, x) |
#oc(a, x) = #oc(a, y), #oc(a0, x) < #oc(a0, y), a0 ∈ y, ∀ a. a ∈ x ∨ a ∈ y → #oc(a, x) = #oc(a, y), a ∈ x ∨ a ∈ y ⊦
Used simplifier rules: oc-zero: ⊦ #oc(a, x) = 0 ↔ ¬ a ∈ x;%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic1%lels-01: ⊦ ¬ m ≤ n ↔ n < m; from specification nat%ler: ⊦ m ≤ m; from specification nat