Let me answer anyway, just in case:
1. first of all, "abab" does not make much sense since I don't see couples;
write it, either (a,b)(a,b) or (aa,bb) or aa:bb (all these are equivalent writings of the same thing)
2. this would simply be described by (A ⊗ B)(A ⊗ B)
(exactly two times); or maybe (A ⊗ B)^2 or (A ⊗ B){2}, with more exotic regexp writings (not presented in class)
3. don't misunderstand "{ (r^n, s^n) } with the SAME n", this is for ALL n (and not for a given single n; but for any n, this n is the same for r and s); makes sense?
(i updated my answer above to clarify further this later point)
1. first of all, "abab" does not make much sense since I don't see couples;
write it, either (a,b)(a,b) or (aa,bb) or aa:bb (all these are equivalent writings of the same thing)
2. this would simply be described by (A ⊗ B)(A ⊗ B)
(exactly two times); or maybe (A ⊗ B)^2 or (A ⊗ B){2}, with more exotic regexp writings (not presented in class)
3. don't misunderstand "{ (r^n, s^n) } with the SAME n", this is for ALL n (and not for a given single n; but for any n, this n is the same for r and s); makes sense?
(i updated my answer above to clarify further this later point)