The functions res, trim, and prune return new modules are chain complexes that
are isomorphic or homotopy equivalent to the old ones.  But they don't return
the maps.  Instead, they cache them somewhere, which isn't very intuitive.  We
need something more uniform.

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Date: Fri, 3 Nov 2006 16:51:46 -0600
From: Dan Grayson <dan@math.uiuc.edu>
To: mike@math.cornell.edu
CC: dan@math.uiuc.edu
Subject: tensor of rings
Reply-to: dan@math.uiuc.edu


If we do T = tensor(R,S) then the user needs a reliable way to get the ring
maps from R and S into T.  Without this, how can anyone reasonably use the
result of graphIdeal?

What should it be?

