Higher Tits indices of algebraic groups, by Viktor Petrov and Nikita Semenov

Let G be a semisimple algebraic group over a field k. We introduce the higher Tits indices of G as the set of all Tits indices of G over all field extensions K/k. In the context of quadratic forms this notion coincides with the notion of the higher Witt indices introduced by M. Knebusch and classified by N. Karpenko and A. Vishik. Next we classify the higher Tits indices for exceptional algebraic groups. Our main tools involve the Chow groups and the Chow motives of projective homogeneous varieties, Steenrod operations as well as the notion of the J-invariant of algebraic groups.

Viktor Petrov <unknown-email-address>
Nikita Semenov <unknown-email-address>