Hey, How do I find the conjugate classes of a dihedral group of order 2n?
And in Sn what is the number of r cycles? I thought it was nCr, but I have been asked to prove it is n!/(r((n-r)!)) ?
Oh wait, that r cycles question..
I can choose elements in nCr ways.
Out of these I fix the least element in the first place. So that there are (r-1) ways to fill the 2nd place and so on. i.e. the cycle say (5,2,7) is replaced by (2,7,5). So ther are (r-1)! ways of doing this. So the total no. of ways is nCr * (r-1)! which is the reqd. nswer.
Am I right?