Fanography

A tool to visually study the geography of Fano 3-folds.

Identification

Fano variety 2-33

blowup of 1-17 in a line

Picard rank
2 (others)
$-\mathrm{K}_X^3$
54
$\mathrm{h}^{1,2}(X)$
0
Mori–Mukai $d$
-9
Hodge diamond and polyvector parallelogram
1
0 0
0 2 0
0 0 0 0
0 2 0
0 0
1
1
0 11
0 0 34
0 0 0 30
0 0 0
0 0
0
Poisson structures

Still open.

Anticanonical bundle
index
1
$\dim\mathrm{H}^0(X,\omega_X^\vee)$
30
$-\mathrm{K}_X$ very ample?
yes
$-\mathrm{K}_X$ basepoint free?
yes
hyperelliptic
no
trigonal
no
Birational geometry

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 the blowup of

  • 1-17, in a curve of genus 0

This variety can be blown up (in a curve) to

  • 3-6, in a curve of genus 1
  • 3-12, in a curve of genus 0
  • 3-18, in a curve of genus 0
  • 3-25, in a curve of genus 0
  • 3-30, in a curve of genus 0
Deformation theory
number of moduli
0
Bott vanishing
holds
$\mathrm{Aut}^0(X)$$\dim\mathrm{Aut}^0(X)$number of moduli
$\mathrm{PGL}_{4;2}$110
Period sequence

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

GRDB
#2
Fanosearch
#54
Extremal contractions
Semiorthogonal decompositions

A full exceptional collection can be constructed using Orlov's blowup formula.

Alternatively, Kawamata has constructed a full exceptional collection for every smooth projective toric variety.

Structure of quantum cohomology

Generic semisimplicity of:

  • small quantum cohomology, proved by Ciolli in 2005, see [MR2168069] , using the description of a 1 or 2-curve blowup of $\mathbb{P}^3$ or $Q^3$
  • small quantum cohomology, proved by Iritani in 2007, see [MR2359850] , using toric geometry
Zero section description

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

variety
$\mathbb{P}^1 \times \mathbb{P}^3$
bundle
$\mathcal{O}(1,1)$

See the big table for more information.

K-stability
  • none are K-stable
  • none are K-polystable
  • none are K-semistable
Seeand the big table for more information.
Coregularity

For this deformation family, every smooth 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.

Futaki invariant

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

This is the computation of Sektnan–Tipler.

Toric geometry

This variety is toric.

Drag to rotate.

It corresponds to ID #19 on grdb.co.uk.