Showing 2000Show all
3 papers · 1 filter
math.AG2000
There are enough Azumaya algebras on surfaces
Stefan Schroeer
Using Maruyama's theory of elementary transformations, I show that the Brauer group surjects onto the cohomological Brauer group for separated geometrically normal algebraic surfac…
math.AG2000
Remarks on the existence of Cartier divisors
Stefan Schroeer
Given an invertible sheaf, does it come from a Cartier divisor? This might fail in presence of embedded components. I give some examples and characterize those invertible sheaves t…
math.AG2000
Normal del Pezzo surfaces containing a nonrational singularity
Stefan Schroeer
Working over a perfect field, I classify normal del Pezzo surfaces with base number one that contain a nonrational singularity. They form a huge infinite hierarchy; contractions of…