User Friedrich Knop

11 votes

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Diagram folding of simple Lie algebras

answered Mar 25, 2017 at 17:09

11 votes

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Wrong Tits-Index of E7 from Springer 's book

answered Jun 30, 2016 at 11:44

11 votes

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Invariant theory for parabolics

answered Jun 21, 2016 at 9:12

10 votes

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Is $(G\rtimes H,H)$ a Gelfand pair iff $G$ is abelian?

answered Jun 15, 2016 at 14:23

10 votes

Canonical bundle of the Lagrangian Grassmannian

answered Aug 15, 2016 at 19:22

10 votes

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Ring of invariants of $\operatorname{SL}_6$ acting on $\Lambda^3 \mathbb C^6$

answered Dec 21, 2016 at 8:43

10 votes

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Understanding a germ of a GIT quotient

answered Apr 11, 2017 at 7:54

10 votes

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Are multiplicity-free representations weight multiplicity free?

answered Aug 23, 2016 at 21:19

10 votes

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Separating closed $SO(p,q)$ orbits by invariant polynomials

answered Aug 27, 2017 at 10:40

9 votes

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Compactification of $PGL(2,\mathbb{C})$

answered Sep 19, 2017 at 21:11

9 votes

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If an equivariant map is smooth on diagonal matrices, is it smooth everywhere?

answered May 27, 2017 at 17:40

9 votes

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Double cosets of $U(n)\times U(n)$ in $U(2n)$

answered Aug 1, 2016 at 9:23

9 votes

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Pushout of group schemes (question on a lemma in SGA3)

answered Jun 21, 2021 at 19:32

9 votes

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Invariant theory over $\mathbb R$

answered Jul 4, 2021 at 13:12

8 votes

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$G/T$ has finitely many $G^\theta$ orbits

answered Apr 15, 2021 at 19:06

8 votes

Bounded Degree in Ring of Symmetric Functions

answered Nov 14, 2017 at 20:55

8 votes

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Polynomial invariants for simple algebraic groups

answered Dec 31, 2018 at 13:37

8 votes

Is the eigenvalue map open?

answered May 16, 2023 at 18:11

8 votes

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If $\pi$ is a prime of a UFD $A$, is $\text{Spec }A$ a coproduct of $\text{Spec }A[\pi^{-1}]$ and $\text{Spec }A_{(\pi)}$ over $\text{Spec Frac }A$?

answered Dec 31, 2023 at 9:56

8 votes

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Non-reduced, non-crystallographic root systems

answered Feb 25, 2017 at 10:27

8 votes

Question on irreducible representation of tensor products

answered Mar 30, 2017 at 15:23

8 votes

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Asymmetric $A \iff B$ proofs

answered Jul 10, 2017 at 15:45

8 votes

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Is the complement of the open $B$-orbit in a spherical variety cut out by one equation?

answered Aug 29, 2017 at 15:12

8 votes

Representation theory over any field

answered Aug 4, 2017 at 11:23

8 votes

Real orbits of Complex Flag Varieties

answered Aug 17, 2016 at 15:19

8 votes

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Is the toric variety associated to this fan a weighted projective space?

answered Jun 8, 2016 at 6:20

8 votes

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Clarification on the definition of a quotient singularity

answered Jun 10, 2016 at 15:45

8 votes

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Geometric construcion of Proj as a quotient by a $\mathbb{G}_m$ action

answered May 9, 2016 at 17:51

8 votes

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representations of $S_k \times S_j$

answered Apr 22, 2016 at 8:46

7 votes

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$G$-orbits in Springer resolution (or, stabilizer actions on Springer fibers)

answered May 27, 2016 at 4:55

Stack Exchange Network

203 Answers

Diagram folding of simple Lie algebras

Wrong Tits-Index of E7 from Springer 's book

Invariant theory for parabolics

Is $(G\rtimes H,H)$ a Gelfand pair iff $G$ is abelian?

Canonical bundle of the Lagrangian Grassmannian

Ring of invariants of $\operatorname{SL}_6$ acting on $\Lambda^3 \mathbb C^6$

Understanding a germ of a GIT quotient

Are multiplicity-free representations weight multiplicity free?

Separating closed $SO(p,q)$ orbits by invariant polynomials

Compactification of $PGL(2,\mathbb{C})$

If an equivariant map is smooth on diagonal matrices, is it smooth everywhere?

Double cosets of $U(n)\times U(n)$ in $U(2n)$

Pushout of group schemes (question on a lemma in SGA3)

Invariant theory over $\mathbb R$

$G/T$ has finitely many $G^\theta$ orbits

Bounded Degree in Ring of Symmetric Functions

Polynomial invariants for simple algebraic groups

Is the eigenvalue map open?

If $\pi$ is a prime of a UFD $A$, is $\text{Spec }A$ a coproduct of $\text{Spec }A[\pi^{-1}]$ and $\text{Spec }A_{(\pi)}$ over $\text{Spec Frac }A$?

Non-reduced, non-crystallographic root systems

Question on irreducible representation of tensor products

Asymmetric $A \iff B$ proofs

Is the complement of the open $B$-orbit in a spherical variety cut out by one equation?

Representation theory over any field

Real orbits of Complex Flag Varieties

Is the toric variety associated to this fan a weighted projective space?

Clarification on the definition of a quotient singularity

Geometric construcion of Proj as a quotient by a $\mathbb{G}_m$ action

representations of $S_k \times S_j$

$G$-orbits in Springer resolution (or, stabilizer actions on Springer fibers)