To: Benedict H. Gross <gross@math.harvard.edu>
On Wed, 3 Mar 2004, Benedict H. Gross wrote:

> I looked at your webpage (which is very cool) but couldn't find
> the answer to the following question. When you defined the Magic
> Triangle in 1981, did you define a triangle of Lie algebras, or Lie
> groups?

Algebra only - from the point of perturbative quantum field theory
one deals only with the Lie algebra generators, the work I did on groups
(field theorists use groups when they study lattice field theories) was on
U(n) only.

> What I found most amusing in the paper with Deligne was
> that we were able to define Lie groups (ie. to specify the isogeny class)
> whose Lie algebras were previously known to be magical.

Actually, I missed that point althogether while skimming through your
article with Deligne. Will clarify that in the "historical" notes.

Predrag