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Francesco Polizzi's user avatar
Francesco Polizzi's user avatar
Francesco Polizzi's user avatar
Francesco Polizzi
  • Member for 6 years, 11 months
  • Last seen this week
53 votes
Accepted

Are diffeomorphic smooth manifolds truly equivalent?

17 votes

Is this group given presentation isomorphic to $\mathbb{Z}_2$, and why?

9 votes
Accepted

Is stabilizer subgroup Normal

9 votes

Cayley–Hamilton and linear dependence

9 votes

The sum of the cubes of three consecutive integers is divisible by $9$

8 votes

Can 2017 be written uniquely as a sum of 2 squares?

8 votes
Accepted

If $x^n$ is a zero-divisor, then $x$ is too.

7 votes

Book on characteristic classes

7 votes

Blowing up $x^2=y^5$ at the origin -- why two blow-ups are needed?

6 votes
Accepted

Fundamental group in flat families

6 votes

Forced conjugation of elements in finite groups

6 votes

Abel's famous "devil quote"

5 votes
Accepted

If $\mathbb{F}(\alpha)$ and $\mathbb{F}(\beta)$ are isomorphic, then $\alpha\mapsto\beta$ is necessarily an isomorphism?

5 votes
Accepted

Dual Number Problem

5 votes
Accepted

Is every group homomorphism the induced homomorphism of a continuous function?

5 votes
Accepted

Inequivalent holomorphic atlases

5 votes

Are there any motivation of dual space and annihilator PURELY in linear algebra?

4 votes

$(\mathbb{R}^{3},\times)$ is a Lie algebra that does not have Lie subalgebras of dimension 2.

4 votes
Accepted

Extension of continuous map in topological space

4 votes

Proving that every symmetric matrix is congruent to the following canonical form

4 votes

Short exact sequence, torus and a finite group

4 votes
Accepted

Last step of Cardano method. Extracting qube roots of complex numbers.

4 votes
Accepted

Applying Riemann-Roch theorem prove that the Riemann sphere has no genus.

4 votes

Deformation Numbers of Genus $g$ Curves

4 votes

Is the set of all matrices of rank less-or-equal to a given number closed?

4 votes

Why are all circles similar? (Why is $\pi$ a constant?)

4 votes
Accepted

Is the interior of a closed complex path is simply connected?

4 votes

For every $n$, there exists a polynomial of degree $n$ with Galois Group $S_n$

4 votes
Accepted

Compactness is a topological property, proof without open covers

4 votes

Matrix that is neither positive semi-definite, nor negative semi-definite, nor indefinite