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Sei. 1978,18, 37. Jochum, C.;Gasteiger, J. J . Chem. InJ Comput. Sci. 1977.17, 113. Bonchev, D.; Balaban, A. T. J . Chem. InJ Comput. Sci. 1981, 21,223. Hendrickson, J. B.; Toczko, A. G. J . Chem. InJ Comp u t . Sci. 1983, 23, 171. Bersohn, M.; Esack, A. Chem. Scr. 1974, 6, 122. Beierbeck, H. J . Chem. InJ Cornput. Sci. 1982, 22, 215. A referee expressed opinion that finding the “right” vertices to excise to obtain the optimal code with a computer will turn out to be an N P complete problem. The problem of graph isomorphism is known to belong to N P problems, but it is not yet known if it is N P complete. At the same time, the problem of subgraph isomorphism is known to be N P complete. Our approach requires (rule C) one to examine numerous rings, not perception of all cycles, which would lead to a N P complete problem as this would include also a search for Hamiltonian cycles, which is a known N P complete problem. Hence, the complexity of our approach is not worse than that of a graph isomorphism problem, but as demonstrated on chemical examples, it is practical for structures of intermediate size and complexity (e.g., having half a dozen rings). Gibson, G. W.; Granito, C. E. Am. Lab. (Fairfield, Conn.) 1972, 4, 27.
LETTERS TO THE EDITOR Dear Sir: Drs.D. F. Zaye and W. V. Metanomski, in their splendid JCICS article [1986, 26(2), 43-44], enumerated well the channels by which science is conveyed. However, in technology not only are the channels enumerated important, but there is another called “reverse engineering”. That is a fancy way of describing the things a child learns the first time he takes apart a clock. (When clocks had gears instead of transistors.) There is much to be learned by looking at a competitor’s factory or formulation or gadget. As a matter of fact, one of the most expensive chemicals sold today ...about $800 a pound ...is used for “potting” electronic devices to frustrate anyone who wants to know what is “inside” them. (Potting is embedding in a thermosetting resin.)
Although I cannot cite specific examples, I am sure that there is a lot of science that can be learned by reverse engineering, and so I suggest that that method be added to our list of means of transferring the culture. One of the things one learns early on in technology is, first, that you do not necessarily need to understand all the scientific principles to make something useful. Second, there is a tremendous advantage when one is attacking a problem in knowing that a solution exists ...as, for example, in another nation. B. J. Luberoff CHEMTECH Summit, New Jersey 07901
