| a ' + x = y + b ', a ∈ y, b ∈ x, c ∈ x ⊦ c = b, y = [], c ∈ y |
⊦ x ≠ [] → (∃ y, a. x = y + a ')
Used simplifier rules: app: ⊦ x + [] = x;%a: ⊦ (x + y) + z = x + y + z;%c-05: ⊦ a ' = x + b ' ↔ a = b ∧ x = [];%in-15: ⊦ x + a ' = y → a ∈ y;%app-06: ⊦ x + a ' = y + b ' ↔ x = y ∧ a = b;%e-02: ⊦ x + a ' ≠ [];%in-append: ⊦ a ∈ x + y ↔ ¬ ¬(a ∈ x ∨ a ∈ y);%in-17: ⊦ a ∈ b ' ↔ a = b;%in-14: ⊦ a ' + x = y → a ∈ y;%e-01: ⊦ a ' + x ≠ [];%in-rec: ⊦ a ∈ b ' + x ↔ ¬ ¬(a = b ∨ a ∈ x);%in-12: ⊦ a ∈ y → a ∈ x + y; Used terms: x