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Let me refer you to:

Page 2, ex. 4

Can you please explain the following step:


Why $f(s')=s'$ ?


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@user6495: That is a 16-page document. You need to be more specific about where. – Zev Chonoles Apr 29 '11 at 22:59
@Zev Chonoles: sorry, just edited it. – user6495 Apr 29 '11 at 23:00
up vote 2 down vote accepted

Hint: We have a map $f:A\rightarrow B$. This makes $B$ into an $A$-module. What is the definition of "$ab$", for $a\in A$ and $b\in B$?

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ab=f(a)b, right? Thanks! Damn it. can't believe I forgot this. – user6495 Apr 29 '11 at 23:06
@user 6495: Exactly right. Don't worry, happens to all of us :) – Zev Chonoles Apr 29 '11 at 23:07

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