Bruno Kahn (Jussieu)
A degree 3 cohomological invariant for certain division algebras.
Abstract: We will associate to a division algebra D of exponent 2 a cohomology class with values in the degree 3 unramified cohomology of its Severi-Brauer variety, with coefficients Q/Z(2). The theorem is that this invariant is nonzero if and only if the index of D is at least equal to 8. Its proof is an application of joint results with Esnault, Levine and Viehweg.
