| b ' + x + a ' = y + a ' + b ' + z ⊦ y = [], a = b, a ∈ x |
⊦ x ≠ [] → (∃ y, a. x = y + a ')
Used simplifier rules: app: ⊦ x + [] = x;%a: ⊦ (x + y) + z = x + y + z;%app-06: ⊦ x + a ' = y + b ' ↔ x = y ∧ a = b;%in-15: ⊦ x + a ' = y → a ∈ y;%neq-02: ⊦ ¬ a ∈ z ∧ a ≠ c → c ' + z ≠ y1 + a ' + x; Used terms: z