| ∀ z. rmdup(y0) \ z = rmdup(y0 \ z) ⊦ a ' + (rmdup(y0) \ z) = a + rmdup(y0 \ z), a ∈ y0, a ∈ z, a ∈ y0 \ z |
∀ z. rmdup(y0) \ z = rmdup(y0 \ z) ⊦ rmdup(y0) \ z = rmdup(y0 \ z), a ∈ z, a ∈ y0
Used simplifier rules: diff-in: ⊦ a ∈ x \ y ↔ a ∈ x ∧ ¬ a ∈ y;%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ x + y = x + z ↔ y = z; (s)% ⊦ a + x = a ' + x; (s)