| ∀ a, b. (x0 -1l a) -l b = (x0 -l b) -1l a ∨ a = b ⊦ a = a0, a = b, (a0 ' + (x0 -1l a)) -l b = ((a0 ' + x0) -l b) -1l a |
b = a0, ∀ a, b. (x0 -1l a) -l b = (x0 -l b) -1l a ∨ a = b ⊦ a = a0, a = b, (a0 ' + (x0 -1l a)) -l b = ((a0 ' + x0) -l b) -1l a
∀ a, b. (x0 -1l a) -l b = (x0 -l b) -1l a ∨ a = b ⊦ b = a0, a = a0, a = b, (a0 ' + (x0 -1l a)) -l b = ((a0 ' + x0) -l b) -1l a
Used formulas: b = a0