Cohomology and the Brauer groups of diagonal surfaces

We present a method for calculating the Brauer group of a surface given by a diagonal equation in the projective space. For diagonal quartic surfaces with coefficients in Q we determine the Brauer groups over Q and Q(i).Comment: 45 page

Effectivity of Brauer-Manin obstructions on surfaces

We study Brauer-Manin obstructions to the Hasse principle and to weak approximation on algebraic surfaces over number fields.Comment: 13 page

On the Brauer group of diagonal quartic surfaces

We obtain an easy sufficient condition for the Brauer group of a diagonal quartic surface D over Q to be algebraic. We also give an upper bound for the order of the quotient of the Brauer group of D by the image of the Brauer group of Q. The proof is based on the isomorphism of the Fermat quartic surface with a Kummer surface due to Masumi Mizukami.Comment: Appendix "The Fermat quartic as a Kummer surface (after Mizukami)", by Sir Peter Swinnerton-Dye

Transcendental obstructions to weak approximation on general K3 surfaces

We construct an explicit K3 surface over the field of rational numbers that has geometric Picard rank one, and for which there is a transcendental Brauer-Manin obstruction to weak approximation. To do so, we exploit the relationship between polarized K3 surfaces endowed with particular kinds of Brauer classes and cubic fourfolds.Comment: 24 pages, 3 figures, Magma scripts included at the end of the source file