| ∀ y. rmdup(x0 + rmdup(y)) = rmdup(x0 + y) ⊦ a ' + rmdup(x0 + rmdup(y)) = a + rmdup(x0 + y), a ∈ y, a ∈ rmdup(y), a ∈ x0, a ∈ x0 + y |
∀ y. rmdup(x0 + rmdup(y)) = rmdup(x0 + y) ⊦ rmdup(x0 + rmdup(y)) = rmdup(x0 + y), a ∈ x0, a ∈ rmdup(y), a ∈ y
Used simplifier rules: ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ x + y = x + z ↔ y = z; (s)% ⊦ a + x = a ' + x; (s)