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Salvo Tringali

Shijiazhuang, Hebei, China

Not all those who wander are lost.

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Top Questions
38 votes

Correspondences between Borel algebras and topological spaces

general-topology measure-theory descriptive-set-theory asked Dec 6, 2011 at 16:09
math.stackexchange.com

21 votes

Is there any non-commutative ring such that every element other than the identity is a zero divisor?

reference-request ra.rings-and-algebras noncommutative-algebra noncommutative-rings asked Jun 20, 2021 at 10:33
mathoverflow.net

18 votes

An elementary, short proof that the group of units of the ring of integers of a number field is finitely generated

nt.number-theory reference-request algebraic-number-theory asked Apr 16, 2017 at 21:11
mathoverflow.net

17 votes

Do $X$ and $Y$ have the same cardinality if their families of finite subsets do?

reference-request set-theory lo.logic asked Jul 2 at 20:51
mathoverflow.net

16 votes

An elementary proof that, for every fixed $n \in \mathbf N^+$, there are infinitely many primes $\equiv -1 \bmod n$

nt.number-theory reference-request prime-numbers elementary-proofs asked Apr 27, 2017 at 15:21
mathoverflow.net

14 votes

The limit superior of $\varphi(2^n-1)/(2^n-1)$

nt.number-theory asked Oct 18, 2017 at 10:37
mathoverflow.net

13 votes

Every measure on a set $X$ extends to the power set of $X$: Consistent or not with ZF?

lo.logic set-theory measure-theory asked Jan 25, 2016 at 21:56
mathoverflow.net

12 votes

On the independence of lower and upper asymptotic and Banach densities

nt.number-theory reference-request ca.analysis-and-odes asked May 16, 2015 at 18:00
mathoverflow.net

12 votes

Bi-orderability of Baumslag-Solitar group $\langle a,b \mid a^{-1} b^m a = b^n\rangle$ and of $\langle a,b \mid a^{-1} b a^m = b^n\rangle$

reference-request gr.group-theory ordered-groups asked Oct 31, 2013 at 10:21
mathoverflow.net

12 votes

Higman's lemma and a manuscript of Erdős and Rado

reference-request co.combinatorics lattices asked Aug 25, 2019 at 16:38
mathoverflow.net

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Top Answers
33
How Composite can $2^n-1$ be, infinitely often?
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26
Sums of sets of lower density 0
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Sets that are not sum of subsets
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13
Polynomials leaving invariant the Gaussian integers
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12
Approximating integers with prime quotients
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12
Is there any non-commutative ring such that every element other than the identity is a zero divisor?
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10
Proof skew-symmetric matrix $A$ exhibits $\vec{x}^T A \vec{x} = 0$
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9
Sums of two squares: positive lower density?
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8
$\zeta^{(k)}(s) < 0$ for $s\in (0,1)$
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Irreducible elements in endomorphism rings
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Open problems with monetary rewards
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6
Perturbation theory for the generalized eigenvalue problem
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6
Applications of Liouville's theorem
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6
A result of Sierpiński on non-atomic measures
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6
How to cite authors from any country correctly?
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6
About Euclidean domains
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sum-sets in a finite field
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6
What are the main structure theorems on finitely generated commutative monoids?
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5
Is there a name for this identity involving series?
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5
How composite $a^n+b$ is?
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5
What is the derivative of $1/g$ in a differential semiring?
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5
Is there some example that nicely extends the multiplication of natural numbers?
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5
Does $R$ is Dedekind-finite imply $\mathbb{M}_n(R)$ is Dedekind-finite
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