From: Tony Smith 17 Feb 2003
Subject: magic triangle
Predrag, my curiosity prompts me to ask about the magic triangle
that you describe in Chapter 21 Exceptional Magic of your
Group Theory web book.
I see a very similar Magic Triangle in the paper of
Pierre Deligne and Benedict Gross on the web at
http://abel.math.harvard.edu/~gross/preprints/Exx.pdf
Your paper and theirs both refer to
P. Deligne, "La série exceptionelle de groupes de Lie,
"C.R. Acad. Sci. Paris, Ser. I, 322, 321 (1996).
Is that where the Magic Triangle was first discussed?
Predrags answer:
No. I introduced this Magic Triangle in my June 1977 Oxford
preprint (available on this website) and published it in
P. Cvitanovic', ``Negative dimensions and $E_7$ symmetry,''
Nucl. Phys. B 188, 373 (1981). See the ``Exceptional
Magic" chapter in the webbok.