Preface

Over the past few years while studying for my doctorate, many times when explaining what my research consisted of, the reaction to my saying that I was ‘‘studying the topic of optimization’’, was always the same: ‘‘Optimization of what?’’. Moreover, it was always accompanied by a puzzled look on the part of the interlocutor. The first time I was rather surprised by such a question and look then, as time passed by, I become accustomed to them. In fact, I found it rather amusing to repeat the same old phrase to different people, irrespective of their age, education, social background or culture, and to be able to foresee their reaction and their answer. On my part, I tried to answer using the simplest words I could find, avoiding any technicality in order to be understood if possible: ‘‘Well—I replied— everything and nothing: I am studying the theory of optimization. It is a general approach, rather mathematical, that you can apply to any problem you like. In particular I am applying it to some test cases, mainly in the fields of thermodynamics and fluid dynamics’’. However, with an even more puzzled look they seemed to say: ‘‘Are you kidding me?’’. To my chagrin, I realized I had not been able to communicate to my listeners any understanding of what I meant. Neither I had any idea on how to explain things in a simpler way. It seemed optimization could not constitute a research topic in itself, being necessarily associated to something more practical. Worse still, it was as if in ‘‘optimization’’ no ‘‘theory’’ was needed since just some common sense was enough, thus, there was nothing to study! I had the overall impression that most people think that optimizing something is a sort of handicraft job in which one would take an object, whatever it is, and with a long build-and-test approach, almost randomly, trying again and again, so would hopefully manage to improve its working. At other times it seemed to me that ‘‘optimization’’ and ‘‘design’’ were thought of as incompatible, with the field of interest of optimization limited to some sort of management issue for industrial processes. For my part, I never thought of it in this way when I started my doctorate, these questions and ideas not even coming to mind when optimization was proposed as