
Please post any and all homework or other textbookstyle problems in one of the Homework & Coursework Questions...

Feb2313 09:24 AM
micromass

1 
35,126 
I am currently taking a number theory course. The professor who teaches the course is very well known in his research...

Oct113 02:58 PM
DeadOriginal

10 
8,957 
I'm having some set theoretic qualms about the following argument for the following statement:
Let V be a vector...

Sep3013 10:42 PM
Office_Shredder

11 
3,593 
Is there any finite dimensional Lie algebra that is not isomorphic to any of the subalgebras contained in GL(n) ?

Sep2913 10:49 AM
Office_Shredder

1 
845 
I am curious:
if f and g are (complex) orthogonal functions, are f* and g also orthogonal? (* denotes complex...

Sep2913 10:27 AM
economicsnerd

2 
749 
okay so I know that the area of the triangle is half the area of the parallelogram, ill try using pictures because...

Sep2913 09:50 AM
SteamKing

1 
1,193 
hello everyone..
if we have a function y=f(x) then inorder to prove linearity we try to justify according to...

Sep2813 04:55 PM
shivaniits

4 
852 
given an sop form of a multi variable boolean expression, how to judge if it is linear or not?
is (x or y) linear? ...

Sep2713 05:22 PM
Erland

5 
1,880 
If AB is invertible, then A and B are invertible for square matrices A and B.
I am curious about the proof of the...

Sep2713 02:57 PM
Erland

14 
8,056 
Hello,
Just discovered this forum as I'm so intensely curious about this question I sought out just such a place!
...

Sep2413 03:12 PM
Erland

2 
1,386 
In his interesting book "Moonshine beyond the Monster", Terry Gannon proposes the interesting thought
He notes...

Sep2213 06:37 PM
nonequilibrium

0 
1,268 
I am not sure that this is the correct forum for this question.
I have multiple sets of 3, 3D (x, y, z) points in...

Sep2213 01:17 PM
Stephen Tashi

4 
1,344 
So I have been heavily trying to understand rotations.
Rotations as i understand is a planar phenomenon. You need at...

Sep2013 09:56 PM
A David

14 
2,313 
Is the following statement true? I am trying to see if I can use it as a lemma for a larger proof:
Let ##V## be a...

Sep2013 05:57 AM
Erland

4 
1,157 
I have a question that i been trying to solve which seam simple but been having trouble. Today I thought about...

Sep1913 11:21 PM
D H

7 
981 
How is the dimension of solution space is nr, where n is the number of unknowns and r is the rank of A.

Sep1913 08:40 AM
Erland

5 
858 
Hey
This is from Numerical analysis course (Legendre polynom)  they gave us the polynomial transformation from to ...

Sep1813 10:29 AM
pasmith

1 
1,003 
Hey!
From MathWorld on solvable group:
But why is that a special case? The way I understand it: the normal...

Sep1813 07:48 AM
nonequilibrium

2 
934 
F(X1,...,Xn) is an invariant polynomial defined on the Lie algebra of a Lie group. The Xi here are left invariant...

Sep1713 07:46 AM
lavinia

0 
921 
A is orthogonal if the A^{1} = A^{T}.
Thus, AA^{T} = I.
However, is the statement A is orthogonal equivalent to...

Sep1713 02:33 AM
UltrafastPED

1 
1,089 
Hello. I started Gallians Contemporary Abstract Algebra today. Is it wise to go through each of the given proofs for...

Sep1713 01:56 AM
Bipolarity

1 
960 
Eigenstates of some observable O are represented by orthonormal vectors in complex Hilbert space.
Is it true that...

Sep1713 01:22 AM
James MC

6 
1,059 
Say I have a linear transformation T:V##\rightarrow##W. Can I necessarily say that T(V)##\subseteq##W?
I feel like...

Sep1613 01:43 PM
verty

6 
1,158 
I wanted to know if there is any way of classifying the set of all nonlinear multivariable functions. I wish to...

Sep1613 01:37 PM
fzero

1 
863 
Hello!
Is there any nice proof that if belongs to the same vectorspace as A and B, then C is in the same...

Sep1613 11:31 AM
fzero

1 
1,012 
I found that the cartan subalgebra of ##sp(4,\mathbb{R})## is the algebra with diagonal matrices in...

Sep1513 12:12 AM
MathematicalPhysicist

4 
958 
The N real numbers x0, ..., xN1 are transformed into the N real numbers X0, ..., XN1 according to one of the formula...

Sep1413 03:27 PM
mathman

1 
742 
Let G be a group and my book defines closure as: For all a,bε G the element a*b is a well defined element of G. Then G...

Sep1413 02:57 PM
bonfire09

4 
901 
Consider a data matrix, X, with zero empirical mean.
What is zero empirical mean?
Could someone please give me...

Sep1313 04:15 PM
mathman

1 
915 
if X= (3, 5, 7) & Y = (2, 4, 1)
What is the 3x3 covariance matrix for X & Y?

Sep1313 04:13 PM
mathman

7 
1,052 
I read that scalar matrices are the center of the ring of matrices. How would I prove this?
Tips are appreciated. It...

Sep1213 10:44 AM
Axiomer

1 
1,323 
http://en.wikipedia.org/wiki/Covariance
I read from the above link that
The sample covariance of N observations...

Sep1213 05:41 AM
DUET

6 
971 
Let ##T: V → V ## be a linear map on a finitedimensional vector space ##V##.
Let ##W## be a Tinvariant subspace of...

Sep1113 04:46 PM
Erland

1 
782 
Hello,
I consider the groups of rotations R=SO(2) and the group T of translations on the 2D Cartesian plane.
Let's...

Sep1113 03:33 PM
mnb96

4 
947 
Is this true? I am studying direct sums and was wondering if the following statement holds? It seems to be true if one...

Sep1013 11:58 PM
Office_Shredder

3 
1,182 
The identity map on the direct sum of V1 and V2 would be i1 composed with p1 + i2 composed with p2. Would such an...

Sep913 09:04 AM
economicsnerd

1 
954 
I'm curious about whether a statement I conjecture about direct sums is true.
Suppose that ##V## is a...

Sep813 05:46 PM
economicsnerd

4 
971 
Hey, how would I graph the plane x + 2y + 3z = 0. We were taught to find the x,y and z intercepts and then connect...

Sep813 06:45 AM
baddin

2 
866 
Let xij be the ith independently drawn observation (i=1,...,N) on the jth random variable (j=1,...,K). These...

Sep713 12:39 PM
UltrafastPED

1 
827 
I've been thinking about a problem I made up. The solution may be trivial or very difficult as I have not given too...

Sep613 10:18 PM
brmath

3 
890 
Could someone please explain it to me what is the difference between Variance and Covariance?

Sep613 03:17 PM
mathman

3 
825 