We define "transfer morphisms" (also called "push-forwards" or "norm morphisms") between coherent Witt groups of schemes along proper morphisms and establish the base change and projection formulae for those. We then use this to define the category of "Witt motives". We also deduce a d\'evissage theorem. Finally, we obtain some results about Witt groups of cellular varieties.
Baptiste Calmes <email@example.com>
Jens Hornbostel <firstname.lastname@example.org>