Motivic equivalence of quadratic forms

Expositor:  Detlev Hoffmann

Institución: Technische Universität Dortmund, Alemania

lunes 03 de agosto a las 12:00 hrs.
Sala de magíster.

Resumen: Let F be a field of characteristic not 2 and let p,q be two nondegenerate quadratic forms of the same dimension over F. We say that p and q are motivically equivalent if the motives of their associated quadrics are equivalent in the category of Chow motives. This category is a difficult concept in algebraic geometry, but fortunately, Vishik found a much more elementary criterion to describe motivic equivalence of quadratic forms. We use this criterion to study when motivically equivalent quadratic forms are similar. This is not always the case (we give counterexamples), but over certain nice fields such as global fields, motivic equivalence always implies similarity. We also compare motivic equivalence and similarity with other types of equivalence relations on quadratic forms, such as birational and stably birational equivalence.