We prove an additivity for evenly (oddly) finite dimensional
objects in distinguished triangles in a triangulated monoidal category
structured by an underlying model monoidal category. In particular, the
result holds in the Q-localized motivic stable homotopy category of
spectra and in Q-localized Voevodsky's category of motives over a
field, char=0. As an application, we show that the motives of schemes
of dimension one (separated and of finite type over a field, char=0)
are finite dimensional.
[Updated June 20, 2003: contains additional citations and corrections of misprints.]
[Updated Jan 5, 2004: should be clearer and more readable now.]