User Salvo Tringali

3 votes

Transcendence on $ \alpha+f(\alpha), \alpha f(\alpha) $ and $ \alpha/f(\alpha) $ where $ \alpha$ is transcendental

answered Jun 19, 2021 at 9:14

3 votes

Accepted

Is there any structural characterization of the rings in which every element other than the identity is a (two-sided) zero divisor?

answered Jun 19, 2021 at 16:07

3 votes

Minimal size of subsets $A,B$ in a finite group $G$ such that $AB=G$

answered Apr 9, 2013 at 12:34

3 votes

Structures that turn out to exhibit a symmetry even though their definition doesn't

answered Jan 13, 2014 at 12:29

3 votes

What is an example of a ring with two (or more) multiplicative right-identities?

answered Dec 23, 2015 at 22:13

3 votes

Subsets of $\mathbb{N}$ whose lower density respects complements

answered Jul 2, 2015 at 15:07

3 votes

Examples of eventual counterexamples

answered Dec 6 at 6:15

3 votes

Examples of cancellative normal semigroups

answered Apr 10 at 4:24

2 votes

Conjecture about commutative semigroups

answered Oct 13 at 4:09

2 votes

What's a non-abelian totally ordered group?

answered Jun 18, 2013 at 11:19

2 votes

Reference for a strong intermediate value theorem for measures

answered Nov 10, 2015 at 21:23

2 votes

Reference to a variant of Abel's summation formula

answered Dec 9, 2015 at 13:10

2 votes

Accepted

Additivity of upper densities with respect to arithmetic progressions of integers

answered Dec 18, 2015 at 16:22

2 votes

Accepted

Superadditivity of the lower density

answered Dec 30, 2015 at 16:44

2 votes

Accepted

Sum of subsequence, over index set of non-zero density, of monotone divergent sum also divergent?

answered Feb 9, 2016 at 15:40

2 votes

Accepted

Looking for a reference to a classical formula for the sum of the base-$b$ digits of an integer

answered Apr 5, 2014 at 7:07

2 votes

Accepted

Regarding sub-additive sequences and Fekete's lemma

answered Apr 9, 2014 at 8:18

2 votes

Conditions for an analogue of Cauchy-Davenport for simple groups

answered May 17, 2015 at 17:13

2 votes

Accepted

Elementary cases of Mihailescu theorem

answered Apr 8, 2013 at 14:02

2 votes

Is every non-invertible element of a commutative von Neumann regular ring a zero-divisor? (answered: yes!)

answered Jun 18, 2021 at 16:57

2 votes

Accepted

Proving that $(\omega(c_1 x_1^n+\cdots+c_kx_k^n))_{n\ge 1}$ is bounded only if $|x_1|=\cdots=|x_k|$ by the Subspace Theorem

answered Nov 15, 2017 at 22:13

2 votes

Subsets of $\mathbb{R}^+$ closed under addition

answered Oct 9, 2022 at 11:59

2 votes

What is the simplest proof that the density of primes goes to zero?

answered Oct 17, 2022 at 21:12

2 votes

Accepted

Apropos of two groups being globally isomorphic iff they are isomorphic

answered Oct 20, 2023 at 7:26

1 vote

Is the class of inverse semigroups globally determined?

answered Nov 9, 2023 at 7:33

1 vote

Problem 0.9.10 in Cohn's "Free Ideal Rings and Localization in General Rings" (CUP, 2006)

answered Mar 12, 2022 at 16:09

1 vote

Accepted

Origins of a theorem on an atomic factorizations in domains and cancellative monoids satisfying the ACCPL and the ACCPR

answered Jan 26, 2022 at 18:14

1 vote

Accepted

What is a "cusp" ("кусок") in relation to Guba's embedding theorem?

answered Nov 5, 2021 at 17:07

1 vote

Reference request: a cousin to the log semiring

answered Feb 18, 2021 at 17:23

1 vote

Reference for a certain derivation on the ring of ordered series over a free monoid

answered Mar 2, 2021 at 17:03

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77 Answers

Transcendence on $ \alpha+f(\alpha), \alpha f(\alpha) $ and $ \alpha/f(\alpha) $ where $ \alpha$ is transcendental

Is there any structural characterization of the rings in which every element other than the identity is a (two-sided) zero divisor?

Minimal size of subsets $A,B$ in a finite group $G$ such that $AB=G$

Structures that turn out to exhibit a symmetry even though their definition doesn't

What is an example of a ring with two (or more) multiplicative right-identities?

Subsets of $\mathbb{N}$ whose lower density respects complements

Examples of eventual counterexamples

Examples of cancellative normal semigroups

Conjecture about commutative semigroups

What's a non-abelian totally ordered group?

Reference for a strong intermediate value theorem for measures

Reference to a variant of Abel's summation formula

Additivity of upper densities with respect to arithmetic progressions of integers

Superadditivity of the lower density

Sum of subsequence, over index set of non-zero density, of monotone divergent sum also divergent?

Looking for a reference to a classical formula for the sum of the base-$b$ digits of an integer

Regarding sub-additive sequences and Fekete's lemma

Conditions for an analogue of Cauchy-Davenport for simple groups

Elementary cases of Mihailescu theorem

Is every non-invertible element of a commutative von Neumann regular ring a zero-divisor? (answered: yes!)

Proving that $(\omega(c_1 x_1^n+\cdots+c_kx_k^n))_{n\ge 1}$ is bounded only if $|x_1|=\cdots=|x_k|$ by the Subspace Theorem

Subsets of $\mathbb{R}^+$ closed under addition

What is the simplest proof that the density of primes goes to zero?

Apropos of two groups being globally isomorphic iff they are isomorphic

Is the class of inverse semigroups globally determined?

Problem 0.9.10 in Cohn's "Free Ideal Rings and Localization in General Rings" (CUP, 2006)

Origins of a theorem on an atomic factorizations in domains and cancellative monoids satisfying the ACCPL and the ACCPR

What is a "cusp" ("кусок") in relation to Guba's embedding theorem?

Reference request: a cousin to the log semiring

Reference for a certain derivation on the ring of ordered series over a free monoid