There seems to be some confusion (including my confusion!) as to the usual notation for ‘bounded above’ chain complexes, etc., on the page category of chain complexes , when I compare the notation with Weibel (and several others). Weibel (page 3) uses $Ch_{-}$ for bounded above , $Ch_{+}$ for bounded below.

]]>I have polished *category of chain complexes* a little more and started a section (but unfinished) with discussion of that and how $Ch_\bullet(\mathcal{A})$ is itself again an abelian category