Cohomological Obstructions for Varieties over $p$-adic Function Fields

Abstract

We introduce various cohomological obstructions for smooth integral varieties over $p$-adic function fields. We show that the unramified obstruction is the finest one among obstructions arising from arithmetic dualities. We also construct an explicit example whose unramified obstruction gives a proper obstruction while Manin obstruction does not. Finally, we compare the unramified obstruction with the descent obstruction.