| ⊦ x -l a ⊆m (y -1l a) -l a ∧ #oc(a, x) ≤ #oc(a, y -1l a) ↔ x -l a ⊆m y -l a ∧ (#oc(a, x) < #oc(a, y) ∨ ¬ a ∈ x) |
x -l a ⊆m y -l a ⊦ #oc(a, x) ≤ #oc(a, y -1l a) ↔ #oc(a, x) < #oc(a, y) ∨ ¬ a ∈ x
Used simplifier rules: del1-del: ⊦ (x -1l a) -l a = x -l a; from specification list-del