Let ? (?) be a finite extension F of odd degree(greater than 1). Show that ? (?2) = ? (?).
See Answer →Is there a finite group with class equation 1+1+2+2+2+2+2+2?
See Answer →Determine, up to isomorphism, all the finite groups with exactly 2 conjugacy classes.
See Answer →Describe the set of primes p for which x² - 11 splits into linear factors over Zp.
See Answer →Find the elementary divisors and invariant factors of
Let H be a finite group and, for some prime p, let P be a p-Sylow subgroup of H which is normal in H. Suppose H is normal in K, where K is a finite group. Then, show that Pis normal in K.
See Answer →Consider the natural action of GL2 on M2
, the set of 2 x 2 real matrices, by left multiplication.
(i) Under this action, if det(x) ≠ 0, show that the stabiliser of x ∈ M2 is {I}, where I is the 2 x 2 identity matrix.
(ii) Suppose that det(x) = 0 in the remaining parts of this exercise. We will show that the stabiliser of x is infinite. If x = 0, the stabiliser of x is GL2. So suppose x ≠ 0. Let us write
Then,
for non-zero λ ∈ R. Why?
(iii) Let be a vector that is not a scalar multiple of
. Show that there is a matrix b =
such that b
= 0 and b
= α
(Hint: Set up two sets of simultaneous equations in two unknowns and argue why they have a solution.)
(iv) Check that I-b is in the stabiliser of x. Also, show that there are infinitely many choices of a for which I - b is invertible.
See Answer →Which of the following statements are true and which are false? Give reasons for your answer.
(a) If a finite group G acts on a finite set S, then Gs1 = Gs2 for all s1, $2 ∈ X.
(b) There are exactly 8 elements of order 3 in S4.
(c)
(d)
(e) For any
Show that there is only one linear fractional transformation that maps three given distinct points, and
in the extended
plane onto three specified distinct points
, and w,3 in the extended w plane.
Find the image of the semi-infinite strip when
. Sketch the strip and its image.
22-1 Prove that the linear fractional transformation maps the circle
into itself. Also prove that
is conformal in
Find the zeros and singularities of the function Also find the residue at the poles.
Find the maximum modulus on the closed circular region defined by
Evaluate de where e is the circle
Find all the singularities of the function