The maximal unipotent finite quotient, unusual torsion in Fano threefolds, and exceptional Enriques surfaces
Langue
en
Article de revue
Ce document a été publié dans
Épijournal de Géométrie Algébrique. 2020-08-19
EPIGA
Résumé en anglais
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 ...Lire la suite >
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.< Réduire
Origine
Importé de halUnités de recherche