I have this exercise, where I'm a little stuck. Any help would be nice.
2) For ideals and in a ring R find
3) Define . Is S multiplicatively closed?
Prove that as an element in and that as an element in .
4) With S as above find for each of following modules;
Well, regarding (1) I know that the sum module is just rows , right? So I would say that the Annulator would be
And (3) I would say yes because ?