We can write (A⊗B)+ as (Ak, Bk), where k ∈ ℤ+.
A+ ≡ An where n ∈ ℤ+.
B+ ≡ Bm where m ∈ ℤ+.
So, A+⊗B+ ≡ (An, Bm) where n ∈ ℤ+ and m ∈ ℤ+.
A+ ≡ An where n ∈ ℤ+.
B+ ≡ Bm where m ∈ ℤ+.
So, A+⊗B+ ≡ (An, Bm) where n ∈ ℤ+ and m ∈ ℤ+.
Note that in (A⊗B)+, the power (k) is the same for A and B.
For A+⊗B+, n and m could be either equal (n=m) or not equal (n≠m).
Hence, (A⊗B)+ is included in A+⊗B+. This is the case when n=m.
