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:--[[User:Nmisner|Neely Misner]] 12:42, 2 October 2008 (UTC)
 
:--[[User:Nmisner|Neely Misner]] 12:42, 2 October 2008 (UTC)
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I could be wrong, but I don't think there is actually a closed form for this particular homomorphism. At least, I wasn't able to find one. We have, however, completely defined <math>\scriptstyle\phi</math> for all of its domain elements, so that suffices as a solution to the exercise.
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:--[[User:Narupley|Nick Rupley]] 12:40, 2 October 2008 (UTC)

Revision as of 07:40, 2 October 2008

We know that phi(7) = 7 and thus we can see that phi7 * 7) = phi(7) * phi(7) by the morphism law which is 49 -30 which equals 19.

Same applies with phi(7^3) it equals 13.

How do we get the elements 23 and 29 to finish the homomorphism?

--Robertsr 10:24, 1 October 2008 (UTC)


For the remaining two elements:

$ \scriptstyle\phi(13*11)\,\,=\,\,\phi(143)\,\,=\,\,\phi(23)\,\,=\,\,\phi(13)\phi(11)\,\,=\,\,13*1\,mod\,30\,\,=\,\,13 $
$ \scriptstyle\phi(19*11)\,\,=\,\,\phi(209)\,\,=\,\,\phi(29)\,\,=\,\,\phi(19)\phi(11)\,\,=\,\,19*1\,mod\,30\,\,=\,\,19 $

--Nick Rupley 01:34, 2 October 2008 (UTC)

I don't quite understand this problem. I get how to map things from U(30) to U(30) but what is the actual morphism that we are trying to find?

--Neely Misner 12:42, 2 October 2008 (UTC)

I could be wrong, but I don't think there is actually a closed form for this particular homomorphism. At least, I wasn't able to find one. We have, however, completely defined $ \scriptstyle\phi $ for all of its domain elements, so that suffices as a solution to the exercise.

--Nick Rupley 12:40, 2 October 2008 (UTC)

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