On Tue, 14 Nov 2006, David Laight wrote:
> Generating a full list of ancestors is one of the things that can get
> (almost) unbounded.

I think it's one do-almost-nothing call per child->parent link in
the graph, plus some list copies per node in the graph.  I think the
problem in the exiting code is all the calls to TargHasAncestor, not
TargInitAncestors.

--apb (Alan Barrett)