| ∀ a, b. (x0 -l a) -l b = (x0 -l b) -l a ⊦ (a0 ' + (x0 -l a)) -l b = ((a0 ' + x0) -l b) -l a, a = a0, b = a0 |
∀ a, b. (x0 -l a) -l b = (x0 -l b) -l a ⊦ (x0 -l a) -l b = (x0 -l b) -l a, a = a0, b = a0
Used simplifier rules: del-n: ⊦ a ≠ b → (b ' + x) -l a = b ' + (x -l a);% ⊦ x + y = x + z ↔ y = z; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list