| a ∈ y ⊦ #oc(a0, x) + #oc(a0, y -1l a) ≤ #oc(a0, (x + y) -1l a) |
#oc(a0, (x + y) -1l a) < #oc(a0, x) + #oc(a0, y -1l a), a ∈ y ⊦ #oc(a0, x) + #oc(a0, y -1l a) = 0
Used simplifier rules: f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic% ⊦ m ≤ n ↔ ¬ n < m; (ss)