Motivic cohomology and unramified cohomology of quadrics

  • Bruno Kahn

    Université Paris 7, France
  • Ramdorai Sujatha

    University of British Columbia, Vancouver, Canada


Abstract. This is the last of a series of three papers where we compute the unramified cohomology of quadrics in degree up to 4. Complete results were obtained in the two previous papers for quadrics of dimension h4 and S11. Here we deal with the remaining dimensions between 5 and 10. We also prove that the unramified cohomology of Pfister quadrics with divisible coefficients always comes from the ground field, and that the same holds for their unramified Witt rings. We apply these results to real quadrics. For most of the paper we have to assume that the ground field has characteristic 0, because we use Voevodsky's motivic cohomology.

Cite this article

Bruno Kahn, Ramdorai Sujatha, Motivic cohomology and unramified cohomology of quadrics. J. Eur. Math. Soc. 2 (2000), no. 2, pp. 145–177

DOI 10.1007/S100970000015