[stamped, Mar 18 1975]
Dear Victor
Thank you for sending me Jim Laurence's answer to the problem I posed to you in my letter of 3/31/75 (copy enclosed.) Hardly anything bearing exactly on this question has been published: the 2 enclosed reprints may say something of the background (labeling; CONGEN).
The molecular structures that CONGEN builds ignore stereoisomers (for the present): i.e., they classify the C atom as S4. At one time I wanted to categorize some stereoisomers. Instead of re-writing the basic program, I thought I would substitute an A4 graph in place of C; the program would then calculate the appropriate symmetries, albeit at some cost in computational efficiency.
Hence the question: what is the smallest A4.
You should note that Ray Carhart had already produced a 2l-node graph, and I thought I had sent that to you. We did not know whether this was the smallest With slings ([diagram]) and higher values we also find one at 22 nodes;
[END PAGE ONE]
[BEGIN PAGE TWO]
[diagram]
Lawrence-Klee A4 (nonplanar) graph
[stamped, Mar 18 1976]
26 nodes
how about putting it in Congen to prove it is A4 (and verify the program again)
Josh