April 15, 1965

Dr. A. Kotzig

Department of Mathematics
University of Bratislava
Bratislava, Czechoslovakia

Dear Dr. Kotzie:

The volume "Theory of Graphs and its Applicatons” has just come to my attention

and I was most interested to see your contribution in it. I would be most greatful
for an exchange of publications (and especially for any Inglish versions or
abstracts you may have).

I have no pretensions as a mathematician, but you may be interested in some
results of our computations of Srivalent graphs in connection with applications
to chemistry. These are being consolidated into a more coherent report.

My main aim is to challenge some graph specialists to make a more orderly analysis
of this set of graphs. I am especially annoyed with the non-polygonal ones,

which become rather intractable (though still manageable even in this clumsy
system) at n 1h.

bj-240f

Is there a convex trivalent polyhedron of which just one edge may not be included
in any Hamilton circuit? (The pentagonal prism is an example which has a pair
b6 edges that are mutually exclusive, as exploited by Tutte for his famous example.

Sincerely yours,

’
} j {.
af a ee
a4

“ Joshua Lederberg }
Professor of Genetics

To be sent by separate mail:

1. DENDRAL-~6h ~ Part I.

2. Topological Mapping of Organic Molecules. Proc. Nat. Acad. Sci. 53:134. 1965.
3. Tables of 10~ and 12-vertex graphs and counts.

4, Note re Dr. Grace's enumeration.

5. Hamilton Circuits of Convex Trivalent Polyhedra (up to 18 vertices)