| ⊦ dups(x + b ' + c ' + a ') ↔ dups(x + b ' + c '), a = b, a = c, a ∈ x |
Used simplifier rules: f: ⊦ dups(x + a ') ↔ a ∈ x ∨ dups(x);% ⊦ a ∈ b ' ↔ a = b; (s)% ⊦ a ≠ b → (a ∈ b ' + x ↔ a ∈ x); (s)% ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list