User Giovanni Moreno

35 votes

4 answers

2k views

Why there is a relation among the second-order minors of a symmetric $4\times 4$ matrix?

asked Jun 12, 2015 at 7:53

14 votes

3 answers

1k views

Is there a "unique" homogeneous contact structure on odd-dimensional spheres?

asked Jun 24, 2014 at 7:50

10 votes

1 answer

584 views

Is there a unique "natural" action of $\mathsf{SL}_{n+1}$ on $\mathbb{R}^n$?

asked Jun 10, 2021 at 9:39

9 votes

1 answer

526 views

What is the total polarization of the determinant?

asked May 27, 2014 at 7:28

8 votes

2 answers

591 views

How to "lift" a transitive group action on a manifold?

asked Sep 29, 2014 at 13:54

8 votes

0 answers

295 views

Co-filtered and pro-finite manifolds, filtered algebras, and differential calculus on them

asked May 12, 2012 at 5:06

8 votes

2 answers

573 views

Contact distributions on $(G_2,P)$-type Cartan geometries in dimension 5

asked Mar 6, 2016 at 8:21

7 votes

1 answer

207 views

Some intuition on the $SL_n$-module $V_{[1,1,...,1]}$

asked Dec 5, 2016 at 11:27

7 votes

2 answers

1k views

What does it mean that the Hessian is proportional to the metric?

asked Jul 31, 2015 at 6:23

6 votes

1 answer

257 views

Is there a canonical split signature metric on $\mathbb{P}^n\times\mathbb{P}^{n\,\ast}$?

asked Oct 19, 2015 at 10:36

6 votes

2 answers

416 views

Symplectic orthogonality and projective duality: how do they work together?

asked Feb 5, 2016 at 7:30

5 votes

1 answer

409 views

Is the Veronese variety "enough" to describe all the $SL(V)$-orbits in $\mathbb{P}(\textrm{Sym}^dV)$?

asked Nov 6, 2015 at 12:41

5 votes

3 answers

479 views

Can the conformal structure on the projective light-cone detect hyperplane sections?

asked Sep 17, 2015 at 8:30

5 votes

0 answers

132 views

Relative invariants of $P\oplus P^*$

asked Sep 23, 2015 at 13:25

5 votes

2 answers

724 views

Is the Lie quadric $Q^3$ isomorphic to the Lagrangian Grassmannian $\operatorname{LG}(2,4)$?

asked May 10, 2014 at 5:32

4 votes

0 answers

419 views

Is there a well-known tautological bundle over $\mathbb{P}(\Lambda^nV)$?

asked Jul 13, 2015 at 19:10

4 votes

1 answer

304 views

Representing groups with two generators as graph automorphisms

asked Apr 16, 2012 at 9:39

4 votes

4 answers

868 views

Submanifolds in the Grassmannian of n-dimensional subspaces determined by a submanifold in the Grassmannian of l-dimensional subspaces

asked Aug 4, 2013 at 20:41

4 votes

1 answer

208 views

Are all bidimensional second-order PDE at most quadratic in the top derivatives of Monge-Ampère type?

asked Dec 8, 2015 at 8:33

4 votes

1 answer

170 views

Does a $G$-structure on $M$ automatically descend to a contact $G$-structure on $\mathbb{P}T^*M$?

asked Feb 1, 2016 at 9:31

4 votes

1 answer

401 views

Invariants of symmetric forms with respect to the symplectic group

asked Feb 12, 2020 at 7:34

4 votes

2 answers

204 views

Is $\mathbb{P}T^*M$ a sub-Riemannian manifold if $M$ is Riemannian?

asked Apr 8, 2016 at 17:47

3 votes

1 answer

167 views

How to embed $S^2\mathbb{C}^2$ into $S^2S^3\mathbb{C}^2$ and get the ideal of the twisted cubic?

asked Apr 14, 2016 at 12:06

3 votes

0 answers

93 views

Invariant Lagrangians of a connection and its derivatives: how do they look like?

asked Mar 21, 2016 at 12:56

3 votes

1 answer

220 views

What is the curved version of the Tits fibration for $G_2$?

asked Nov 2, 2016 at 10:29

3 votes

1 answer

210 views

How many second-order PDEs can be obtained from a contact EDS?

asked Mar 1, 2016 at 11:07

3 votes

1 answer

501 views

Osculating spaces and distributions on (real) Grassmannian manifold

asked May 5, 2012 at 8:55

2 votes

1 answer

1k views

Tautological and normal bundles over flag manifolds and jet bundles

asked Apr 18, 2012 at 10:19

2 votes

1 answer

231 views

How to characterize the dual of an isotropic hyperplane?

asked Aug 2, 2012 at 9:09

2 votes

1 answer

259 views

Is any $G$-set a coset geometry (in the sense of Tits-Buekenhout)?

asked Jan 16, 2013 at 13:21

Stack Exchange Network

36 Questions

Why there is a relation among the second-order minors of a symmetric $4\times 4$ matrix?

Is there a "unique" homogeneous contact structure on odd-dimensional spheres?

Is there a unique "natural" action of $\mathsf{SL}_{n+1}$ on $\mathbb{R}^n$?

What is the total polarization of the determinant?

How to "lift" a transitive group action on a manifold?

Co-filtered and pro-finite manifolds, filtered algebras, and differential calculus on them

Contact distributions on $(G_2,P)$-type Cartan geometries in dimension 5

Some intuition on the $SL_n$-module $V_{[1,1,...,1]}$

What does it mean that the Hessian is proportional to the metric?

Is there a canonical split signature metric on $\mathbb{P}^n\times\mathbb{P}^{n\,\ast}$?

Symplectic orthogonality and projective duality: how do they work together?

Is the Veronese variety "enough" to describe all the $SL(V)$-orbits in $\mathbb{P}(\textrm{Sym}^dV)$?

Can the conformal structure on the projective light-cone detect hyperplane sections?

Relative invariants of $P\oplus P^*$

Is the Lie quadric $Q^3$ isomorphic to the Lagrangian Grassmannian $\operatorname{LG}(2,4)$?

Is there a well-known tautological bundle over $\mathbb{P}(\Lambda^nV)$?

Representing groups with two generators as graph automorphisms

Submanifolds in the Grassmannian of n-dimensional subspaces determined by a submanifold in the Grassmannian of l-dimensional subspaces

Are all bidimensional second-order PDE at most quadratic in the top derivatives of Monge-Ampère type?

Does a $G$-structure on $M$ automatically descend to a contact $G$-structure on $\mathbb{P}T^*M$?

Invariants of symmetric forms with respect to the symplectic group

Is $\mathbb{P}T^*M$ a sub-Riemannian manifold if $M$ is Riemannian?

How to embed $S^2\mathbb{C}^2$ into $S^2S^3\mathbb{C}^2$ and get the ideal of the twisted cubic?

Invariant Lagrangians of a connection and its derivatives: how do they look like?

What is the curved version of the Tits fibration for $G_2$?

How many second-order PDEs can be obtained from a contact EDS?

Osculating spaces and distributions on (real) Grassmannian manifold

Tautological and normal bundles over flag manifolds and jet bundles

How to characterize the dual of an isotropic hyperplane?

Is any $G$-set a coset geometry (in the sense of Tits-Buekenhout)?