Let E/F be an algebraic extension and let K and L be
intermediate fields (i.e. F ⊆ K ⊆ E and F ⊆ L ⊆ E). Assume that [K
: F] and [L : F] are finite and that at least K/F or L/F is Galois.
Prove that [KL : F] = [K : F][L : F] / [K ∩ L : F] .
Theorem: Let K/F be a field extension and let a ∈ K be algebraic
over F. If deg(mF,a(x)) = n, then
1. F[a] = F(a).
2. [F(a) : F] = n, and
3. {1, a, a2 , ..., an−1} is a basis for F(a).
let E be a finite extension of a field F of prime
characteristic p, and let K = F(Ep)
be the subfield of E obtained from F by adjoining the pth powers of
all elements of
E. Show that F(Ep) consists of all finite linear combinations of
elements in Ep with
coefficients in F.
Let E be an extension field of a finite field F, where F has q
elements. Let a in E be an element which is algebraic over F with
degree n. Show that F(a) has q^n elements. Please provide an unique
answer and motivate all steps carefully. I also prefer that the
solution is provided as written notes.
Let F and G~be two vector fields in R2 . Prove that
if F~ and G~ are both conservative, then F~ +G~ is also
conservative. Note: Give a mathematical proof, not just an
example.
The question is: Let G be a finite group, H, K be normal
subgroups of G, and H∩K is also a normal subgroup of G. Using
Homomorphism theorem ( or First Isomorphism theorem) prove that
G/(H∩K) is isomorphism to a subgroup of
(G/H)×(G/K). And give a example of group G with
normal subgroups H and K such that G/(H∩K) ≆ (G/H)×(G/K), with
explanation.
I was trying to find some solutions for the isomorphism proof
part, but they all seems to...
Question 1. Let V and W be finite dimensional vector spaces over
a field F with dimF(V ) = dimF(W) and let T : V → W be a linear
map. Prove there exists an ordered basis A for V and an ordered
basis B for W such that [T] A B is a diagonal matrix where every
entry along the diagonal is either a 0 or a 1.
Hint 1. Suppose A = {~v1, . . . , ~vn}...
Let V and W be finite dimensional vector spaces over a field F
with dimF(V ) = dimF(W ) and let T : V → W be a linear map. Prove
there exists an ordered basis A for V and an ordered basis B for W
such that [T ]AB is a diagonal matrix where every entry along the
diagonal is either a 0 or a 1.
Throughout this question, let G be a finite group, let p be a
prime, and suppose that H ≤ G is such that [G : H] = p.
Let G act on the set of left cosets of H in G by left
multiplication (i.e., g · aH = (ga)H). Let K be the set of elements
of G that fix every coset under this action; that is,
K = {g ∈ G : (∀a ∈ G) g · aH...