Ok, so that makes sense. Now I am lost as to what the two phis should look like. phi1: G ->G/H and phi2: K -> K/L. However, I don't know what these look like. I am so bad at proofs.
Homework Statement
Suppose H is a normal subgroup G and L is a subgroup of K. Then (G x K)/(H x L) is isomorphic to (G/H) x (K/L)
Homework Equations
The Attempt at a Solution
I know that I have to use the First Isomorphism Theorem, but in order to do that I need some function phi...
Homework Statement
For every ϕ in Aut(G), ϕ(Z(G))= Z(G).
Homework Equations
Z(G):={g in G| gh=hg for all h in G}
The Attempt at a Solution
I haven't made too much progress on this one. I know that if I let g be an element of Z(G) that I need to prove that For every ϕ(g) is also...
is there any way I can eliminate |H intersect K|=1 by assuming it does and finding a contradiction? I am not sure I am at the ability level to do what you suggested.
Homework Statement
Suppose |G| = pqr where p, q, and r are distinct primes. If H is a subgroup of G and K is a subgroup of G with |H| = pq and |K| = qr, then |H intersect K| = q.
Homework Equations
NA
The Attempt at a Solution
I have so far:
Let a be an element of H intersect K...