We determine the essential dimension of the spin group Spin as an algebraic group over a field of characteristic 2, for at least 15. In this range, the essential dimension is the same as in characteristic not 2. In particular, it is exponential in n. In contrast, the essential dimension of the orthogonal groups is smaller in characteristic 2. We also find the essential dimension of Spin in characteristic 2 for at most 10.
Cite this article
Burt Totaro, Essential dimension of the spin groups in characteristic 2. Comment. Math. Helv. 94 (2019), no. 1, pp. 1–20DOI 10.4171/CMH/452