
Topology Question
Hey! Any help will be greatly appreciated!
1. This is a 2 part question. I got the first part.
i)compute
I know how to do this one, the answer is Z, but I don't get how to do part 2 of the problem.
ii) describe all its covering spaces and the corresponding subgroups of
Thank you!

Subgroups of Z are of the form <n>={k*n  k \in Z}, that is, all the multiples of a single integer n. When n = 0 <0>={0} is the trivial subgroup.
Each subgroup corresponds to a covering of X=S1 V S2, p : E_n > X, with n sheets, as follows: Divide the unit circle S^1 evenly to n parts, using the n unit roots of 1 . Attach a sphere to each , the covering map p is defined to be on the circle and the identity map on the sphere sending the n attaching points to the single attaching point of .
The universal covering space is a straight line with a sphere attached to each of its integer points. That is, a line with infinitely (countable) many spheres attached.