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F p -représentations semi-stables

Xavier Caruso (2011)

Annales de l’institut Fourier

Soient p un nombre premier et K un corps p -adique à corps résiduel parfait (par exemple une extension finie de F p ) dont l’indice de ramification absolue est noté e . Afin d’étudier les « représentations semi-stables de p -torsion » de G K = Gal ( K ¯ / K ) , Breuil a défini pour tout entier positif r < p - 1 plusieurs catégories de ( φ , N ) -modules filtrés de torsion. Dans cet article, nous décrivons la structure de ces catégories dans le cas général (seul le cas e r < p - 1 avait été étudié de façon systématique jusqu’à présent).

Factorial Fermat curves over the rational numbers

Peter Malcolmson, Frank Okoh, Vasuvedan Srinivas (2016)

Colloquium Mathematicae

A polynomial f in the set {Xⁿ+Yⁿ, Xⁿ +Yⁿ-Zⁿ, Xⁿ +Yⁿ+Zⁿ, Xⁿ +Yⁿ-1} lends itself to an elementary proof of the following theorem: if the coordinate ring over ℚ of f is factorial, then n is one or two. We give a list of problems suggested by this result.

Factorization of point configurations, cyclic covers, and conformal blocks

Michele Bolognesi, Noah Giansiracusa (2015)

Journal of the European Mathematical Society

We describe a relation between the invariants of n ordered points in projective d -space and of points contained in a union of two linear subspaces. This yields an attaching map for GIT quotients parameterizing point configurations in these spaces, and we show that it respects the Segre product of the natural GIT polarizations. Associated to a configuration supported on a rational normal curve is a cyclic cover, and we show that if the branch points are weighted by the GIT linearization and the rational...

Failure of the Hasse principle for Châtelet surfaces in characteristic 2

Bianca Viray (2012)

Journal de Théorie des Nombres de Bordeaux

Given any global field k of characteristic 2 , we construct a Châtelet surface over k that fails to satisfy the Hasse principle. This failure is due to a Brauer-Manin obstruction. This construction extends a result of Poonen to characteristic 2 , thereby showing that the étale-Brauer obstruction is insufficient to explain all failures of the Hasse principle over a global field of any characteristic.

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