In this paper we define and study the triangulated category of mixed motives
over a field. At least in the case when there is resolution of
singularities, we are able to prove that this category is has a natural
duality and that the Hom-groups between Tate objects are canonically
isomorphic to the corresponding higher Chow groups. A detailed of summary of
results of the paper is given in the first section.
This replaces an earlier version.