ABSTRACT
When I started my first steps in theoretical chemistry at the beginning of the 1990’s in Cuba, I was very excited about the use of graph-theoretic ideas to represent molecules and describe their properties. While attending
at a conference I had the opportunity to chat with a well-known theoretical chemist who was visiting Cuba and asking his opinion about “chemical graph theory.” His lapidary response was: “Chemical graph theory cannot go beyond Hückel method, and so it is dead.” Then, partially because of my ignorance and partially because of the fact that I was listening everyday many things I do not believe in, I decided to give rid of the expert advice and centre my investigation around molecules, the Hückel method and graph theory. I was in my mid 20’s ‘Non tamen ista meos mutabunt saecula mores: unus quisque sua noverit ire via.’ (But age shall still not change my habits: let each man be allowed to go his own way) [1].
