Local fundamental groups of surface singularities in characteristic p.
Soient un espace analytique affinoïde réduit sur un corps complet pour une valeur absolue non archimédienne, sa réduction canonique et un point de la variété algébrique affine . Ce travail décrit la singularité du point à l’aide d’objets associés à l’espace : la localisation formelle qui est une -algèbre noethérienne de spectre maximal et dont la réduction est ; un complété formel qui est une -algèbre noethérienne dont la réduction est . Les résultats essentiels sont obtenus...
We study matrix factorizations of a potential W which is a section of a line bundle on an algebraic stack. We relate the corresponding derived category (the category of D-branes of type B in the Landau-Ginzburg model with potential W) with the singularity category of the zero locus of W generalizing a theorem of Orlov. We use this result to construct push-forward functors for matrix factorizations with relatively proper support.
Working over an algebraically closed field k of any characteristic, we determine the matrix factorizations for the-suitably graded-triangle singularities of domestic type, that is, we assume that (a,b,c) are integers at least two satisfying 1/a + 1/b + 1/c > 1. Using work by Kussin-Lenzing-Meltzer, this is achieved by determining projective covers in the Frobenius category of vector bundles on the weighted projective line of weight type (a,b,c). Equivalently, in a representation-theoretic context,...
We show that a complex normal surface singularity admitting a contracting automorphism is necessarily quasihomogeneous. We also describe the geometry of a compact complex surface arising as the orbit space of such a contracting automorphism.