Subject: RE: 2 questions Date: Wed, 17 Mar 2004 09:02:15 -0000 From: "Neil Strickland" To: "Don Davis" > Is the full subcategory of finite objects in the stable category > equivalent, as a triangulated category, to a full subcategory of the > derived category of an abelian category? Can the abelian category be > chosen to be symmetric monoidal and so that S^0 corresponds to a > resolution of the unit object? Let A be an abelian category, let X be an object of D(A), and let Y be the cofibre of 2.1_X : X --> X. One can then write down a nullhomotopy of the map 2.1_Y. However, if M is the mod 2 Moore spectrum then 2.1_M is not nullhomotopic. It follows that the stable homotopy category does not embed in D(A). Neil