Show that the groups of the following orders have a normal Sylow
subgroup.
(a) |G| = pq where p and q are
primes.
(b) |G| = paq where p and
q are primes and q < p.
(c) |G| = 4p where p is a prime greater than
four.
Let G be a nonabelian group of order 253=23(11), let P<G be a
Sylow 23-subgroup and Q<G a Sylow 11-subgroup.
a. What are the orders of P and Q. (Explain and include any
theorems used).
b. How many distinct conjugates of P and Q are there in G? n23?
n11? (Explain, include any theorems used).
c. Prove that G is isomorphic to the semidirect product of P and
Q.
For p a given prime number, define the p-adic norm | * |p as
follows on Q: Given q in Q, we can write it as a product q =
(p^m)(a/b) with a,b integers which are not divisible by p, and m an
integer which is uniquely determined by q (check that m is indeed
uniquely determined by q). Then define |q|p = p^(-m).
Check that Q with distance dp(q1,q2) = |q1 - q2|p is a metric
space (here q1-q2...
Prove that in a finite cyclic group, each subgroup has size dividing the size of the group. Conversely, given a positive divisor of the size of the group, there is a subgroup of that size.