| a ∈ rmdup(x0) + y, ∀ y. rmdup(rmdup(x0) + y) = rmdup(x0 + y) ⊦ rmdup(rmdup(x0) + y) = rmdup((a ' + x0) + y), a ∈ x0 |
a ∈ y, ∀ y. rmdup(rmdup(x0) + y) = rmdup(x0 + y) ⊦ rmdup(rmdup(x0) + y) = rmdup(x0 + y), a ∈ x0
Used simplifier rules: rm-in-02: ⊦ a ∈ rmdup(x) ↔ a ∈ x;%rm-in-04: ⊦ a ∈ y → rmdup(a ' + x + y) = rmdup(x + y);%a: ⊦ (x + y) + z = x + y + z; from specification list%in-append: ⊦ a ∈ x + y ↔ ¬ ¬(a ∈ x ∨ a ∈ y); from specification list