DEPARTMENT OF CHEMISTRY
CORNELL UNIVERSITY

ITHACA, NEW YORK
Sept. 9, 1965

Prof. J. Lederberg,
Dept. of Genetics
Stanford University

Dear Prof. Lederberg:

Thank you tor your last letter
ex, laining the notation for non—-hamiltonian
circuits.

No, we are not making any gauche graphs.
However, my own opinion is that this
"sopological hiatus" will be first filled
by molecules of the type showr below.

L don't see any need on my part of the
complete set of graphs at this point,
but I would be very interested if
your proz.rams can produce the complete
set of graphs on n vertices, n odd, with
n-l vertices trivalent, and one vertex :
divalent. Tnese would be representations
of anions, cations or radicals.

Sincerely,