Fanography

1-5 1-7

Fano variety 1-6

section of half-spinor embedding of a connected component of $\mathrm{OGr}_+(5,10)$ by codimension 7 subspace

Picard rank

1 (others)

$-\mathrm{K}_X^3$

12

$\mathrm{h}^{1,2}(X)$

7

Mori–Mukai $d$

12

No nontrivial holomorphic Poisson structures.

See Loray–Pereira–Touzet.

index

1

$\dim\mathrm{H}^0(X,\omega_X^\vee)$

9

$-\mathrm{K}_X$ very ample?

yes

$-\mathrm{K}_X$ basepoint free?

yes

hyperelliptic

no

trigonal

no

This variety is rational.

This variety is stably rational.

The Weyl group associated to the KKMR decomposition is $\{e\}$; see the Weyl-group table for sources and conventions.

This variety is primitive.

This variety is fibre-like, i.e. it can appear as the fibre of a Mori fibre space.

number of moduli

18

Bott vanishing

does not hold

The following period sequences are associated to this Fano 3-fold:

GRDB

#150

Fanosearch

#7

The naive atomic decomposition has atom dimensions $2+1+1$.

A standard semiorthogonal decomposition is $\langle \mathrm{D}^{\mathrm{b}}(C_7), \mathcal{E}_5, \mathcal{O}_X \rangle$.

Both decompositions are recorded in Böhning–Graf von Bothmer–Su'a.

By Hertling–Manin–Teleman we have that quantum cohomology cannot be generically semisimple, as $\mathrm{h}^{1,2}\neq 0$.

Fano 3-folds from homogeneous vector bundles over Grassmannians gives the following description(s):

variety

$\operatorname{OGr}^+(5,10)$

bundle

$\mathcal{O}(\frac{1}{2})^{\oplus7}$

variety

$\operatorname{Gr}(2,5)$

bundle

$\mathcal{U}^{\vee}(1)\oplus \mathcal{O}(1)$

See the big table for more information.

• every member is K‑stable
• every member is K‑polystable
• every member is K‑semistable

• the book

For this deformation family, the general member has coregularity 0.

The generic and uniform statements are due to Avilov–Loginov–Przyjalkowski; the existence of a smooth member of coregularity zero in every family is due to Zhakupov.

See coregularity for terminology.

For every K-polystable member, the Futaki invariant vanishes identically on the entire Kähler cone.

This is the computation of Sektnan–Tipler.

The Hilbert scheme of conics is the symmetric square of a smooth curve of genus 7.

Its Hodge diamond is