| rmdup(z) = y + a ' + z0, a0 ∈ y + a ' + z0, a0 ∈ x0, a ∈ z, a0 ∈ z ⊦ # rmdup(x0) = # rmdup((y0 + y) + z0), a0 ∈ z0, a0 ∈ y, a0 ∈ y0, a ∈ x0, a ∈ y0, a ∈ y, a ∈ z0 |
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ ¬ a ∈ x → (a ∈ b ' + x ↔ a = b); (s)% ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s)