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No One
  • Member for 7 years, 8 months
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17 votes
1 answer
240 views

For what kind of infinite subset A of $\mathbb Z$ and irrational number $\alpha$, is $\{e^{k\alpha \pi i}: k\in A \}$ dense in $S^1 $?

13 votes
1 answer
1k views

What is the motivation for Murray-von Neumann equivalence

10 votes
2 answers
1k views

Tietze extension theorem in LCH spaces

7 votes
1 answer
503 views

Is every affine open subset of a locally Noetherian scheme also Noetherian?

7 votes
4 answers
196 views

The real function $f$ such that $\log \cdots \log (f)$ is strictly convex on its domain for any number of $\log$'s

6 votes
1 answer
748 views

Groups of order $360$ have a subgroup of order $10$

6 votes
2 answers
570 views

Is there a locally compact, locally connected, Hausdorff and second countable space that is "nowhere locally Euclidean"?

6 votes
1 answer
403 views

Norm of a character in a non-unital Banach algebra without approximate identity

6 votes
1 answer
2k views

Any set of linearly independent and commuting vector fields CAN be realized (locally) as partial derivatives of a local coordinate

6 votes
2 answers
3k views

How to prove Liouville's theorem for subharmonic functions

6 votes
1 answer
420 views

Why is a deck transformation completely determined by where it sends a single point?

6 votes
3 answers
846 views

An infinite dimensional CW complex always has infinitely many non-trivial homology groups?

6 votes
1 answer
365 views

Is there a way to decompose a polynomial $xy+f(x,y)$ into the product of two convergent power series $x+g(x,y)$ and $y+h(x,y)$?

5 votes
1 answer
428 views

The example of an exact functor that doesn't commute with colimits in abelian category

5 votes
2 answers
949 views

Why does sheafification functor being left adjoint imply that the presheaf kernel is a sheaf kernel

5 votes
3 answers
539 views

prove that $(xy-2,x^2-2)$ is a maximal ideal of $\mathbb Q[x,y]$

5 votes
2 answers
965 views

Complete the short exact sequence $0\to \mathbb Z\to A\to Z_n \to 0$

5 votes
1 answer
820 views

is there a sufficient and necessary condition for which the equality in Minkowski inequality holds when $p= \infty$?

5 votes
1 answer
396 views

$\mathcal M(K)$ is an $\mathcal{l}_1-$sum of $L_1(\mu)$ spaces

5 votes
1 answer
278 views

Rearrangement of Schauder basis

5 votes
2 answers
128 views

Motivations of studying $C^r$ manifolds when $r<\infty$

5 votes
1 answer
1k views

The characteristic polynomial of $A$ is $x^n$ if and only if $\text{Tr}(A^i)=0$ for all $1\le i \le n$. [duplicate]

5 votes
2 answers
157 views

There is no ring map $\mathbb C[x] \to \mathbb C[x]$ swapping the prime ideals $(x-1)$ and $(x)$

5 votes
1 answer
253 views

Eigenfunctions of Laplace-Beltrami operator

5 votes
2 answers
291 views

Is $SL_2(\mathbb Z)$ a maximal discrete subgroup in $SL_2(\mathbb R)$?

5 votes
1 answer
269 views

Parabolic subgroup of a Lie group (as oppose to algebraic group)

5 votes
0 answers
132 views

A Gap in the Proof of the Duffin-Schaeffer's theorem

5 votes
2 answers
199 views

Does Frobenius norm (not operator 2 norm) preserve the positive semidefinite order of matrices?

4 votes
1 answer
105 views

Direct proof for any homeomorphism on $[0,1]$ having zero entropy

4 votes
2 answers
88 views

Does $a_n b_n \to e$ imply $b_n a_n \to e$ in a locally compact group?

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