User Mikhail Borovoi

7 votes

1 answer

338 views

A characteristic-free proof that the action of a connected algebraic group $G$ on the fundamental group of a $G$-variety is trivial

asked Feb 28, 2011 at 14:16

7 votes

0 answers

303 views

Albrecht Fröhlich's text `Groupoids, groupoid spaces and cohomology' (1965)

asked Jul 28, 2013 at 18:05

7 votes

1 answer

477 views

Conjugation of the quotient of $\mathrm{SL}(n,\mathbb{C})$ by a finite subgroup

asked Jan 30, 2015 at 11:46

7 votes

2 answers

669 views

Élie Cartan's paper "Les groupes réels simples, finis et continus" of 1914

asked Jun 30, 2020 at 12:22

7 votes

3 answers

676 views

Infinite Galois descent for finitely generated commutative algebras over a field

asked Aug 2, 2018 at 16:19

7 votes

2 answers

330 views

Explicit description of SU(2,2)/U

asked Aug 27, 2018 at 13:02

7 votes

1 answer

445 views

Imperfect Tate (cup product) pairing in Galois cohomology?

asked Nov 23, 2019 at 21:48

7 votes

2 answers

918 views

Is this exact sequence known?

asked Sep 4, 2022 at 13:46

7 votes

1 answer

342 views

Explicit cocycles for the first Galois cohomology of a $p$-adic torus

asked Oct 17, 2021 at 15:44

7 votes

1 answer

570 views

Smooth morphism of smooth varieties with fibres isomorphic to an affine space

asked May 9, 2021 at 14:44

6 votes

1 answer

144 views

Finite $\Gamma$-modules with trivial $H^2$, where $\Gamma$ is a group of order 2

asked Mar 20, 2021 at 14:49

6 votes

0 answers

496 views

The Tate-Nakayama theorem and inflation

asked Nov 25, 2021 at 21:07

6 votes

1 answer

179 views

Restriction vs. multiplication by $n$ in Tate cohomology

asked Sep 19, 2022 at 13:43

6 votes

1 answer

659 views

Anti-holomorphic involutions of a complex linear algebraic group

asked Sep 23, 2019 at 18:49

6 votes

1 answer

210 views

Finite group ${\rm Sp}_4({\Bbb F}_3)$: involutions coming from a 4-dimensional complex representation

asked May 17, 2020 at 14:20

6 votes

2 answers

366 views

Twisted forms with real points of a real Grassmannian

asked Aug 10, 2023 at 12:18

6 votes

2 answers

271 views

Group homology for a metacyclic group

asked Nov 8, 2023 at 15:56

6 votes

1 answer

286 views

Classification of algebraic groups of the types $^1\! A_{n-1}$ and $^2\! A_{n-1}$

asked Oct 4, 2023 at 18:12

6 votes

0 answers

173 views

Computer programs for decomposition groups?

asked May 30 at 17:55

6 votes

2 answers

532 views

The action of the center on the extended Dynkin diagram

asked Mar 10, 2015 at 16:49

6 votes

0 answers

411 views

Real approximation for homogeneous spaces of linear algebraic groups

asked Dec 28, 2010 at 15:36

6 votes

3 answers

745 views

Quotient of a reductive group by a non-smooth central finite subgroup

asked Feb 24, 2010 at 13:51

6 votes

2 answers

353 views

The Tits classes of simply connected simple real groups

asked Jan 28, 2018 at 14:22

5 votes

0 answers

164 views

The group of automorphisms a pair $(G,X)$ where $X$ is a spherical homogeneous space of $G$

asked Apr 15, 2017 at 10:39

5 votes

0 answers

206 views

Real field of definition of an abelian variety of CM-type?

asked Sep 2, 2016 at 15:22

5 votes

1 answer

618 views

Non-vanishing of the Tate-Shafarevich kernel in group cohomology

asked Jun 10, 2016 at 17:52

5 votes

1 answer

189 views

Matrix from a homomorphism of simply connected groups

asked Aug 3, 2015 at 17:19

5 votes

3 answers

1k views

Splitting of a division algebra with an involution of second kind

asked May 12, 2010 at 14:39

5 votes

2 answers

586 views

Quotient of a reductive group by a non-smooth subgroup

asked Mar 28, 2013 at 14:15

5 votes

2 answers

399 views

Conjugation of homogeneous spaces

asked Jan 8, 2013 at 12:57

Stack Exchange Network

142 Questions

A characteristic-free proof that the action of a connected algebraic group $G$ on the fundamental group of a $G$-variety is trivial

Albrecht Fröhlich's text `Groupoids, groupoid spaces and cohomology' (1965)

Conjugation of the quotient of $\mathrm{SL}(n,\mathbb{C})$ by a finite subgroup

Élie Cartan's paper "Les groupes réels simples, finis et continus" of 1914

Infinite Galois descent for finitely generated commutative algebras over a field

Explicit description of SU(2,2)/U

Imperfect Tate (cup product) pairing in Galois cohomology?

Is this exact sequence known?

Explicit cocycles for the first Galois cohomology of a $p$-adic torus

Smooth morphism of smooth varieties with fibres isomorphic to an affine space

Finite $\Gamma$-modules with trivial $H^2$, where $\Gamma$ is a group of order 2

The Tate-Nakayama theorem and inflation

Restriction vs. multiplication by $n$ in Tate cohomology

Anti-holomorphic involutions of a complex linear algebraic group

Finite group ${\rm Sp}_4({\Bbb F}_3)$: involutions coming from a 4-dimensional complex representation

Twisted forms with real points of a real Grassmannian

Group homology for a metacyclic group

Classification of algebraic groups of the types $^1\! A_{n-1}$ and $^2\! A_{n-1}$

Computer programs for decomposition groups?

The action of the center on the extended Dynkin diagram

Real approximation for homogeneous spaces of linear algebraic groups

Quotient of a reductive group by a non-smooth central finite subgroup

The Tits classes of simply connected simple real groups

The group of automorphisms a pair $(G,X)$ where $X$ is a spherical homogeneous space of $G$

Real field of definition of an abelian variety of CM-type?

Non-vanishing of the Tate-Shafarevich kernel in group cohomology

Matrix from a homomorphism of simply connected groups

Splitting of a division algebra with an involution of second kind

Quotient of a reductive group by a non-smooth subgroup

Conjugation of homogeneous spaces