Non-injectivity of the map from the Witt group of a variety to the Witt group of its function field, by Burt Totaro

We exhibit a smooth complex affine 5-fold whose Witt group of quadratic forms does not inject into the Witt group of the quotient field. The dimension 5 is the smallest possible. The example depends on relating Witt groups, mod 2 Chow groups, and Steenrod operations.


Burt Totaro <b.totaro@dpmms.cam.ac.uk>