HI Swlabr! nice to see you again.

In the book its written that $\displaystyle 5 \leq n$.

you can see this link too:

http://www.mathhelpforum.com/math-he...lp-168487.html
I dont understand the meaning of $\displaystyle (a \text{ } b \ldots c)^{\sigma}$....

You have raised an element in A to the power $\displaystyle \sigma$. Can you please explain it if its not so much trouble. This must be some standard notation but i have not yet come across it.

I have started reading the chapter on group actions just today so i dont know orbit-stabilizer theorem yet. I will read it and then try the question again.

Thanks for comment on my third question.