On the obstruction to the Hasse principle for multinorm equations

Abstract

We investigate local-global principles for multinorm equations over a global field. To this extent, we generalize work of Drakokhrust and Platonov to provide explicit and computable formulae for the obstructions to the Hasse principle and weak approximation for multinorm equations. We illustrate the scope of this technique by extending results of Bayer-Fluckiger--Lee--Parimala, Demarche--Wei and Pollio.