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Salvo Tringali

Shijiazhuang, Hebei, China

Not all those who wander are lost.

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Top Questions
36 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

17 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

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

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

13 votes

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

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

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

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

11 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

11 votes

How to express in a diplomatic, but not too subtle, way that an old (and popular) notion should be dismissed in favor of a new (and better) one?

expressions asked Apr 2, 2017 at 16:51
english.stackexchange.com

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Top Answers
32
How Composite can $2^n-1$ be, infinitely often?
mathoverflow.net

25
Sums of sets of lower density 0
mathoverflow.net

17
Sets that are not sum of subsets
mathoverflow.net

13
Polynomials leaving invariant the Gaussian integers
mathoverflow.net

12
Approximating integers with prime quotients
mathoverflow.net

11
Is there any non-commutative ring such that every element other than the identity is a zero divisor?
mathoverflow.net

10
Proof skew-symmetric matrix $A$ exhibits $\vec{x}^T A \vec{x} = 0$
math.stackexchange.com

9
Sums of two squares: positive lower density?
mathoverflow.net

8
$\zeta^{(k)}(s) < 0$ for $s\in (0,1)$
mathoverflow.net

7
Irreducible elements in endomorphism rings
mathoverflow.net

7
Open problems with monetary rewards
mathoverflow.net

6
Perturbation theory for the generalized eigenvalue problem
mathoverflow.net

6
Applications of Liouville's theorem
mathoverflow.net

6
A result of Sierpiński on non-atomic measures
mathoverflow.net

6
How to cite authors from any country correctly?
mathoverflow.net

6
About Euclidean domains
mathoverflow.net

6
sum-sets in a finite field
mathoverflow.net

6
What are the main structure theorems on finitely generated commutative monoids?
mathoverflow.net

5
Is there a name for this identity involving series?
math.stackexchange.com

5
How composite $a^n+b$ is?
mathoverflow.net

5
What is the derivative of $1/g$ in a differential semiring?
mathoverflow.net

5
Is there some example that nicely extends the multiplication of natural numbers?
mathoverflow.net