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  • Member for 6 years, 10 months
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9 votes

Projection is an open map

4 votes
Accepted

Convergence of infinite series of log function

4 votes
Accepted

A question about a limit

3 votes

If A is a countable set, how can I show that A has countably many finite subsets?

3 votes
Accepted

If F is normal over E and E is normal over K then F need not be normal over K

3 votes

(dis)prove: M compact if and only if every closed ball in M in compact.

3 votes
Accepted

Series convergence radius proximity

3 votes

Show each infinite set $S \subset \mathbb R$ contains a countably infinite subset

3 votes

Does $\sum \limits_{k=1}^{\infty} \frac{\cos(k)-\cos(k+1)}{k}$ converge?

3 votes
Accepted

Let $f$ be continuous on $X$ and $(x_n)$ be a Cauchy sequence on $X$. Show that $(f(x_n))$ doesnt have to be a Cauchy sequence...

3 votes
Accepted

Find all continuous $f$ that $f(xy) = xf(y) + yf(x)$.

3 votes

Prove that [0,1] is connected.

2 votes

Find a Continuous and bijective function but not homeomorphic

2 votes

If a field $F$ is infinite, show that the ring homomorphism $\eta : F[x]\to C(F)$ is one-to-one.

2 votes
Accepted

$\sqrt {144} = 12$ How can I find it without calculator?

2 votes

At which values of $x_0$ does $\lim\limits_{x \rightarrow x_0} g(x)$ exist?

2 votes

$\mathbb{R} \setminus \{ 0 \} $ direct product

2 votes

Showing a basis for polynomials

2 votes

Prove that $13\sqrt{2}$ is irrational.

2 votes

Boundary points and isolated points of $\Bbb{Q}$

2 votes

prove $x \mapsto x^2$ is continuous

2 votes

Undergraduate Analysis Book

2 votes

Prove that $\lim _{n\rightarrow \infty }\dfrac{n^{3}+1}{n^{4}+4}=0$

2 votes
Accepted

prove that $\operatorname{Hom}_\Bbb{Z}(\Bbb{Z}/n\Bbb{Z},A)\cong A_n.$

2 votes
Accepted

Clarification on Outer Measure (Folland)

2 votes
Accepted

Find the Fourier transform of $f(x)=\alpha, ~\alpha\in\mathbb{C}$.

1 vote

A question about the condition for one-to-one linear transformation

1 vote
Accepted

The set of all matrices with trace 1 is path connected.

1 vote
Accepted

Prove: if $\lim \frac{s_n}n=L\neq0$, then the sequence $s_n$ is not bounded.

1 vote
Accepted

Question regarding a subset E open relative to some subset Y of metric space X

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