| ¬ a0 ∈ y, ∀ a, y. #oc(a, x0 \ y) = #oc(a, x0) ∨ a ∈ y ⊦ a0 = a, #oc(a, (a0 ' + x0) \ y) = #oc(a, x0), a ∈ y |
∀ a, y. #oc(a, x0 \ y) = #oc(a, x0) ∨ a ∈ y ⊦ a0 = a, #oc(a, x0 \ y) = #oc(a, x0), a ∈ y, a0 ∈ y
Used simplifier rules: oc-n: ⊦ a ≠ b → #oc(a, b ' + x) = #oc(a, x);%a: ⊦ (x + y) + z = x + y + z; from specification list%c: ⊦ a + x = a ' + x; from specification list%diff-n: ⊦ ¬ a ∈ y → (a ' + x) \ y = a + (x \ y); from specification list-set