| a ∈ z, ∀ y, z. (x0 + y) \ z = (x0 \ z) + (y \ z) ⊦ ((a ' + x0) + y) \ z = ((a ' + x0) \ z) + (y \ z) |
a ∈ z, ∀ y, z. (x0 + y) \ z = (x0 \ z) + (y \ z) ⊦ (x0 + y) \ z = (x0 \ z) + (y \ z)
Used simplifier rules: diff-y: ⊦ a ∈ y → (a ' + x) \ y = x \ y;%a: ⊦ (x + y) + z = x + y + z; from specification list