| ∀ a, y. x0 \ (a ' + y) = (x0 -l a) \ y, a0 = a ∨ a0 ∈ y ⊦ x0 \ (a ' + y) = ((a0 ' + x0) -l a) \ y |
⊦ a ≠ b → (b ' + x) -l a = b ' + (x -l a)
¬ a ≠ a0, ∀ a, y. x0 \ (a ' + y) = (x0 -l a) \ y, a0 = a ∨ a0 ∈ y ⊦ x0 \ (a ' + y) = ((a0 ' + x0) -l a) \ y
a ≠ a0, ∀ a, y. x0 \ (a ' + y) = (x0 -l a) \ y, a0 = a ∨ a0 ∈ y ⊦ x0 \ (a ' + y) = (a0 ' + (x0 -l a)) \ y
Used terms: a, x0, a0