| ∀ z. rmdup(y0) \ z = rmdup(y0 \ z) ⊦ rmdup(a ' + y0) \ z = rmdup((a ' + y0) \ z) |
⊦ rmdup(a ' + x) = (a ∈ x ⊃ rmdup(x);a ' + rmdup(x))
∀ z. rmdup(y0) \ z = rmdup(y0 \ z) ⊦ (a ∈ y0 ⊃ rmdup(y0);a ' + rmdup(y0)) \ z = rmdup((a ' + y0) \ z)
Used terms: y0, a