| ⊦ ¬ #oc(a, x) < #oc(a, x -1l b) |
#oc(a, x) < #oc(a, x -1l b), a ∈ x -1l b, a ∈ x ⊦
Used simplifier rules: oc-zero: ⊦ #oc(a, x) = 0 ↔ ¬ a ∈ x;%in-01-01: ⊦ a ∈ x -1l b → a ∈ x; (forward) from specification list-del%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic1