Homework Statement
Let G be a finite group and K a normal subgroup of G
If |K|=p where p is a prime
Prove that |G/CG(K)| divides p-1
Homework Equations
The Attempt at a Solution
I must show that |G| / |CG(K)| * something = p-1
I figured a good place to start would be to...
Homework Statement
Let G be a group and K be a normal subgroup of G.
Let x be an element of G
Define Ax: K-->K given by Ax(k)=xkx-1
Prove that B: G-->Aut(K) given by B(x)=Ax is a well defined group homomorphism
Homework Equations
The Attempt at a Solution
I found...
Homework Statement
If A=<x> is a cyclic group of order 9 and B=<y> is a cyclic group of order 7. Deduce that Aut(A) is isomorphic to Aut(B)
Homework Equations
The Attempt at a Solution
I already proved that Aut(A) and Aut(B) are cyclic but I don't understand how they can be...
Homework Statement
Suppose that J is an ideal of R, and consider the ring R/J = {r + J | r 2 R}.
Prove that X is an ideal of R/J is and only if there is an ideal I of R containing J such
that J c I c R.
Homework Equations
The Attempt at a Solution
Suppose K= < x > is a cyclic group with 2 elements and H= S3 is symmetric group with 6 elements. Find all different cyclic subgroups of G= H x K.
Now since K is generated by x with 2 elements, I have K= {1,x} and H= {1, (12), (13), (23), (123), (132)}
What I am confused about is finding...