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Alex's user avatar
Alex's user avatar
Alex
  • Member for 12 years, 8 months
  • Last seen more than a month ago
10 votes

Connected metric spaces with at least 2 points are uncountable.

8 votes
Accepted

The sign of a given permutation

7 votes

Banach spaces over fields other than $\mathbb{C}$?

7 votes
Accepted

The Rapidity of the Exponential Function Towards Infinity

7 votes

Results that came out of nowhere.

6 votes
Accepted

What is hyperspace in linear algebra?

6 votes
Accepted

exponent manipulation - $4^{21} \cdot 5^{11} = 2 \cdot 10^{n}$ - what is $n$?

4 votes

Can One use mathematica or maple online?

4 votes

Is the integral as an operator linear?

4 votes
Accepted

Relation between congruence subgroups. $\Gamma(M)\Gamma(N) = \Gamma(\gcd(M,N))$

4 votes
Accepted

Sources on Several Complex Variables

4 votes

$\sum a_{n}^{2}$ converges $\Rightarrow\sum \frac{a_{n}}{n}$ converges

3 votes

$\mathbb{Z}/n\mathbb{Z}$ is not flat

3 votes
Accepted

Matrices representing the same linear transformation

3 votes
Accepted

Finding constant speed

3 votes

Proof that cube has 24 rotational symmetries

2 votes
Accepted

Understanding of the proof of "$d$ solutions for $kx \equiv l \pmod{m}$"

2 votes

How to solve this very quickly?

2 votes

Computing ideal intersections in polynomial rings

2 votes

How do we determine if the set of rational numbers and the set of all english sentences are countable or not?

2 votes

What is 'zero of multiplicity' and 'counting multiplicity'?

2 votes
Accepted

Linearly disjoint field extensions and the tensor product

2 votes
Accepted

Constructing a rational map between two elliptic curves

2 votes

Efficient way to find Galois group

2 votes
Accepted

Polynomials and common roots

2 votes

A sequence converges $\iff$ it's Cauchy. Proof of ($\Leftarrow$) (Abbott p 59 t2.6.4)

2 votes
Accepted

Proving harmonic function is zero

1 vote

Suppose $KA = {\bf0}$ and $K$ is idempotent. Define $G = (A-K)^{-1}$. Prove that (i) $AG = I-K$; (ii) $AGA = A$; and (iii) $AGK = {\bf0}$.

1 vote
Accepted

Boundary on $R^3$ about Stoke's theorem.

1 vote
Accepted

Finding a subspace $\ U \oplus T= R^4 $