Displaying similar documents to “A limit linear series moduli scheme”

Geometry of the genus 9 Fano 4-folds

Frédéric Han (2010)

Annales de l’institut Fourier

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We study the geometry of a general Fano variety of dimension four, genus nine, and Picard number one. We compute its Chow ring and give an explicit description of its variety of lines. We apply these results to study the geometry of non quadratically normal varieties of dimension three in a five dimensional projective space.

Codimension 3 Arithmetically Gorenstein Subschemes of projective N -space

Robin Hartshorne, Irene Sabadini, Enrico Schlesinger (2008)

Annales de l’institut Fourier

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We study the lowest dimensional open case of the question whether every arithmetically Cohen–Macaulay subscheme of ℙ N is glicci, that is, whether every zero-scheme in ℙ 3 is glicci. We show that a general set of n ≥ 56 points in ℙ 3 admits no strictly descending Gorenstein liaison or biliaison. In order to prove this theorem, we establish a number of important results about arithmetically Gorenstein zero-schemes in ℙ 3 .

Integral models for moduli spaces of G -torsors

Martin Olsson (2012)

Annales de l’institut Fourier

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Given a finite tame group scheme G , we construct compactifications of moduli spaces of G -torsors on algebraic varieties, based on a higher-dimensional version of the theory of twisted stable maps to classifying stacks.

On the S-fundamental group scheme

Adrian Langer (2011)

Annales de l’institut Fourier

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We introduce a new fundamental group scheme for varieties defined over an algebraically closed (or just perfect) field of positive characteristic and we use it to study generalization of C. Simpson’s results to positive characteristic. We also study the properties of this group and we prove Lefschetz type theorems.

Stable twisted curves and their r -spin structures

Alessandro Chiodo (2008)

Annales de l’institut Fourier

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The subject of this article is the notion of r -spin structure: a line bundle whose r th power is isomorphic to the canonical bundle. Over the moduli functor M g of smooth genus- g curves, r -spin structures form a finite torsor under the group of r -torsion line bundles. Over the moduli functor M ¯ g of stable curves, r -spin structures form an étale stack, but both the finiteness and the torsor structure are lost. In the present work, we show how this bad picture can be definitely...