# Grassmannian.info

A periodic table of (generalised) Grassmannians.

## Orthogonal Grassmannian $\OGr(7,15)$

There exist other realisations of this Grassmannian:
Basic information
dimension
28
index
14
Euler characteristic
128
Betti numbers
$\mathrm{b}_{ 1 } = 1$, $\mathrm{b}_{ 2 } = 1$, $\mathrm{b}_{ 3 } = 1$, $\mathrm{b}_{ 4 } = 2$, $\mathrm{b}_{ 5 } = 2$, $\mathrm{b}_{ 6 } = 3$, $\mathrm{b}_{ 7 } = 4$, $\mathrm{b}_{ 8 } = 5$, $\mathrm{b}_{ 9 } = 5$, $\mathrm{b}_{ 10 } = 6$, $\mathrm{b}_{ 11 } = 7$, $\mathrm{b}_{ 12 } = 7$, $\mathrm{b}_{ 13 } = 8$, $\mathrm{b}_{ 14 } = 8$, $\mathrm{b}_{ 15 } = 8$, $\mathrm{b}_{ 16 } = 8$, $\mathrm{b}_{ 17 } = 8$, $\mathrm{b}_{ 18 } = 7$, $\mathrm{b}_{ 19 } = 7$, $\mathrm{b}_{ 20 } = 6$, $\mathrm{b}_{ 21 } = 5$, $\mathrm{b}_{ 22 } = 5$, $\mathrm{b}_{ 23 } = 4$, $\mathrm{b}_{ 24 } = 3$, $\mathrm{b}_{ 25 } = 2$, $\mathrm{b}_{ 26 } = 2$, $\mathrm{b}_{ 27 } = 1$, $\mathrm{b}_{ 28 } = 1$, $\mathrm{b}_{ 29 } = 1$
$\mathrm{Aut}^0(\OGr(7,15))$
$\mathrm{PSO}_{ 16 }$
$\pi_0\mathrm{Aut}(\OGr(7,15))$
$1$
$\dim\mathrm{Aut}^0(\OGr(7,15))$
120
Projective geometry
minimal embedding

$\OGr(7,15)\hookrightarrow\mathbb{P}^{ 127 }$

degree
23178480
Hilbert series
1, 128, 6435, 183040, 3476330, 48542208, 530803988, 4751252480, 35968466040, 236100700160, 1370306329288, 7142954259456, 33870128161700, 147644397683200, 596921685945750, 2255119616006400, 8012241391386375, 26919578022480000, 85939988076028125, 261792476262720000, ...
Exceptional collections

No full exceptional collection is known for $\mathbf{D}^{\mathrm{b}}(\OGr(7,15))$. Will you be the first to construct one? Let us know if you do!

Kuznetsov–Polishchuk have constructed an exceptional collection of maximal length in MR3463417. Can you prove it's full?

Quantum cohomology

The small quantum cohomology is generically semisimple.

The big quantum cohomology is generically semisimple.

The eigenvalues of quantum multiplication by $\mathrm{c}_1(\OGr(7,15))$ are given by:

Homological projective duality