Counter-examples to a conjecture of Karpenko via truncated Brown-Peterson cohomology

Victor Petrov, Alois Wohlschlager, Egor Zolotarev

Let $G$ be a split semisimple linear algebraic group and let $X$ denote the generically twisted variety of Borel subgroups in $G$. Nikita Karpenko conjectured that the map from the…