1. I : fset(ℕ)
2. i : ℕ
3. j : ℕ
4. ¬i ∈ I
5. x : names(I)
6. x = i ∈ ℤ
⊢ <j> = <x> ∈ Point(dM(I+j))
{ DVar `x' }
5. x : ℕ
6. x ∈ I
7. x = i ∈ ℤ