\begin{equation} \DeclareMathOperator\Gr{Gr} \DeclareMathOperator\LGr{LGr} \DeclareMathOperator\OGr{OGr} \DeclareMathOperator\SGr{SGr} \DeclareMathOperator\Kzero{K_0} \DeclareMathOperator\index{i} \DeclareMathOperator\rk{rk} \end{equation}

Grassmannian.info

A periodic table of (generalised) Grassmannians.

Quadric $\mathrm{Q}^{9}$

Betti numbers
\begin{align*} \mathrm{b}_{ 1 } &= 1 \\ \mathrm{b}_{ 2 } &= 1 \\ \mathrm{b}_{ 3 } &= 1 \\ \mathrm{b}_{ 4 } &= 1 \\ \mathrm{b}_{ 5 } &= 1 \\ \mathrm{b}_{ 6 } &= 1 \\ \mathrm{b}_{ 7 } &= 1 \\ \mathrm{b}_{ 8 } &= 1 \\ \mathrm{b}_{ 9 } &= 1 \\ \mathrm{b}_{ 10 } &= 1 \end{align*}
Basic information
dimension
9
index
9
Euler characteristic
10
Betti numbers
$\mathrm{b}_{ 1 } = 1$, $\mathrm{b}_{ 2 } = 1$, $\mathrm{b}_{ 3 } = 1$, $\mathrm{b}_{ 4 } = 1$, $\mathrm{b}_{ 5 } = 1$, $\mathrm{b}_{ 6 } = 1$, $\mathrm{b}_{ 7 } = 1$, $\mathrm{b}_{ 8 } = 1$, $\mathrm{b}_{ 9 } = 1$, $\mathrm{b}_{ 10 } = 1$
$\mathrm{Aut}^0(\mathrm{Q}^{9})$
$\mathrm{SO}_{ 11 }$
$\pi_0\mathrm{Aut}(\mathrm{Q}^{9})$
$1$
$\dim\mathrm{Aut}^0(\mathrm{Q}^{9})$
55
Projective geometry
minimal embedding

$\mathrm{Q}^{9}\hookrightarrow\mathbb{P}^{ 10 }$

degree
2
Hilbert series
1, 11, 65, 275, 935, 2717, 7007, 16445, 35750, 72930, 140998, 260338, 461890, 791350, 1314610, 2124694, 3350479, 5167525, 7811375, 11593725, ...
Exceptional collections
  • Kapranov constructed a full exceptional sequence in 1988, see MR0939472.