| ∀ y. rmdup(rmdup(x0) + y) = rmdup(x0 + y) ⊦ rmdup((a ' + rmdup(x0)) + y) = rmdup((a ' + x0) + y), a ∈ x0, a ∈ rmdup(x0) + y |
∀ y. rmdup(rmdup(x0) + y) = rmdup(x0 + y) ⊦ a ' + rmdup(rmdup(x0) + y) = rmdup((a ' + x0) + y), a ∈ rmdup(x0), a ∈ y, a ∈ x0
Used simplifier rules: rmdup-n: ⊦ ¬ a ∈ x → rmdup(a ' + x) = a + rmdup(x);%rm-in-03: ⊦ ¬ a ∈ rmdup(x) → ¬ a ∈ x;% ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a + x = a ' + x; (s)