Fanography

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

Identification

Fano variety 1-14

complete intersection of 2 quadrics in $\mathbb{P}^5$

Picard rank
1 (others)
$-\mathrm{K}_X^3$
32
$\mathrm{h}^{1,2}(X)$
2
Hodge diamond and polyvector parallelogram
1
0 0
0 1 0
0 2 2 0
0 1 0
0 0
1
1
0 0
0 3 15
0 0 0 19
0 0 0
0 0
0
Anticanonical bundle
index
2
del Pezzo of degree 4
$X\hookrightarrow\mathbb{P}^{5}$
$\dim\mathrm{H}^0(X,\omega_X^\vee)$
19
$-\mathrm{K}_X$ very ample?
yes
$-\mathrm{K}_X$ basepoint free?
yes
hyperelliptic
no
trigonal
no
Birational geometry

This variety is rational.


This variety is primitive.

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

  • 2-10, in a curve of genus 1
  • 2-16, in a curve of genus 0
  • 2-19, in a curve of genus 0

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

Deformation theory
number of moduli
3
Bott vanishing
does not hold
$\mathrm{Aut}^0(X)$ $\dim\mathrm{Aut}^0(X)$ number of moduli
$0$ 0 3
Period sequence

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

GRDB
#75
Fanosearch
#2
Semiorthogonal decompositions

There exist interesting semiorthogonal decompositions, but this data is not yet added.

Structure of quantum cohomology

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

Zero section description

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

variety
$\mathbb{P}^5$
bundle
$\mathcal{O}(2)^{\oplus 2}$

See the big table for more information.

Hilbert schemes of curves

The Hilbert scheme of lines is an abelian surface.

Its Hodge diamond is

1
2 2
1 4 1
2 2
1