Fanography

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

Identification

Fano variety 2-20

blowup of 1-15 in a twisted cubic

Picard rank
2 (others)
$-\mathrm{K}_X^3$
26
$\mathrm{h}^{1,2}(X)$
0
Hodge diamond and polyvector parallelogram
1
0 0
0 2 0
0 0 0 0
0 2 0
0 0
1
1
0 0*
0 3* 6
0 0 0 16
0 0 0
0 0
0
* indicates jumping of $\operatorname{Aut}^0$
its dimension takes on the values 0, 1
Anticanonical bundle
index
1
$\dim\mathrm{H}^0(X,\omega_X^\vee)$
16
$-\mathrm{K}_X$ very ample?
yes
$-\mathrm{K}_X$ basepoint free?
yes
hyperelliptic
no
trigonal
no
Birational geometry

This variety is rational.


This variety is the blowup of

  • 1-15, in a curve of genus 0
Deformation theory
number of moduli
3
Bott vanishing
does not hold
$\mathrm{Aut}^0(X)$ $\dim\mathrm{Aut}^0(X)$ number of moduli
$\mathbb{G}_{\mathrm{m}}$ 1 0
$0$ 0 3
Period sequence

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

GRDB
#87
Fanosearch
#46
Extremal contractions
Semiorthogonal decompositions

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

Structure of quantum cohomology
Zero section description

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

variety
$\operatorname{Gr}(2,5) \times \mathbb{P}^2$
bundle
$\mathcal{U}^{\vee}_{\operatorname{Gr}(2,5)}(0,1) \oplus \mathcal{O}(1,0)^{\oplus 3}$

See the big table for more information.