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4 votes
1 answer
382 views

Formula for genus of a Fano variety

This is a simple question, just looking for a reference for a formula. As far I understand the genus of a prime Fano $n$-fold is defined to be the genus of a complete intersection of $n-1$ smooth ...
Nick L's user avatar
  • 6,995
2 votes
0 answers
282 views

Global Torelli and local Torelli for Fano threefolds (need reference)

It is known that in general Globally Torelli does not imply the local Torelli theorem, see Is the Torelli map an immersion? Globally Torelli means that the period map $\mathcal{P}$ is injective and ...
user41650's user avatar
  • 1,982
2 votes
0 answers
109 views

arithmetic del Pezzo surfaces in comparison with del Pezzo surfaces over a field

A del Pezzo surface is a smooth, 2-dimensional projective variety $X$ with ample anticanonical divisor, i.e. a 2-dimensional Fano variety. I am interested in the arithmetic analogue, a 2-dimensional ...
PrimeRibeyeDeal's user avatar
15 votes
2 answers
1k views

How does one prove that the complete intersection of a quadric and a cubic of $\mathbb P^5$ is unirational?

The question is stated in the title, but I would like to add some motivation. I've been teaching a course on complex tori and abelian varieties this semester and I would like to end it by showing ...
rita's user avatar
  • 6,253
3 votes
1 answer
609 views

Semiorthogonal decompositions for Fano 3-folds and 4folds

Let $X$ be a projective Fano 3-fold or 4-fold and let $D^b(X)$ be the bounded derived category of coherent sheaves on $X$. For what $X$ is it known a semi orthogonal decomposition into indecomposable ...
DannyBoy's user avatar