Groups of homomorphisms of abelian groups

  • #1
Hello everybody!
I've just started with studying group homorphisms and tensor products, so i am still not very sure if i undertstand the subject correct. I am stuck with a question and i would ask you for some help or hints how to proceed...

What i have to do is to describe ##Hom(\mathbb{Q}/\mathbb{Z},\mathbb{Q})## and ##Hom(\mathbb{Q},\mathbb{Q}/\mathbb{Z})##. I know that both ##\mathbb{Q}/\mathbb{Z}## and ##\mathbb{Q}## are abelian groups, ##\mathbb{Q}/\mathbb{Z}## as a ##\mathbb{Z}##-module is finitely generated, but ##\mathbb{Q}## as a ##\mathbb{Z}##-module is not finitely generated.
Can anybody help me with this problem? How is it meant "to describe the groups of homomorphisms"?
Thank you in advance!
 

Answers and Replies

  • #2
lavinia
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A couple of things that may help
(Since Z is not a group under multiplication, you must be referring to addition)

- Q/Z is a torsion group. That is: every element is of finite order. Q has no elements of finite order.

- Try to find a set of Z generators of Q. Do the reciprocals of the prime numbers work?


BTW: Why do you think Q/Z is a finitely generated Z module?
 
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