The maximal unipotent finite quotient, unusual torsion in Fano threefolds, and exceptional Enriques surfaces
Language
en
Article de revue
This item was published in
Épijournal de Géométrie Algébrique. 2020-08-19
EPIGA
English Abstract
We introduce and study the maximal unipotent finite quotient for algebraic group schemes in positive characteristics. Applied to Picard schemes, this quotient encodes unusual torsion. We construct integral Fano threefolds ...Read more >
We introduce and study the maximal unipotent finite quotient for algebraic group schemes in positive characteristics. Applied to Picard schemes, this quotient encodes unusual torsion. We construct integral Fano threefolds where such unusual torsion actually appears. The existence of such threefolds is surprising, because the torsion vanishes for del Pezzo surfaces. Our construction relies on the theory of exceptional Enriques surfaces, as developed by Ekedahl and Shepherd-Barron.Read less <
Origin
Hal imported