Professor Berarducci on Corrado...#

Corrado is - and always was - passioned about not only science, but technology as well. Always extremely up-to-date about the latest news and products, he had no hesitation whatsoever in proposing them to his students. I learnt how to use the TeXas Instruments during his programming course. You must keep in mind those were the early 80’s and I had taken an exam, only one year before, in which we were required to write a program on punched cards. Those cards were then fed into the “mouth” of a large VAX machine that took up a whole wall. If you got only one small hole wrong, you had to throw the card away and start anew. Nowadays you only need to press DEL and the last character gets canceled. Anyway, the tiny TeXas Instruments were then the latest technological invention. To each student would Corrado propose, at the beginning of each year, a personalized project to be completed on those little programmable machines. We were to write both the program and a written report. I was given the task to design a tree data structure that would dynamically evolve, while keeping reasonably balanced. Another student was asked to implement an algorithm which would take as input the description of a knot (yes, a knot), and provide as output the sequence of moves needed to untie it. Those algorithms were both coming from research papers, no piece of cake for rookie students, even less so since we were to implement them on those TeXas Instrument machines which didn’t even have recursive calls available. Corrado, though, was able to motivate us and would give each of us a task suited to our specific capabilities, so that, by the end of the year, everybody had completed his or her project: one wouldn’t even fathom not to.

As a teacher he was very effective: all I have learnt during that course, I never forgot and never will. Infected by his enthusiasm and by his continuous spurs, we were constantly under the impression to not only assimilate knowledge, but also individually contribute new findings. As a student I had progressed in only one year from punched cards to the TeXas Instruments, but I had not seen the real wonder yet. I saw it for the first time on Corrado’s desk, at his home, and I was flabbergasted. Back home, I told my dad that professor Boehm had a computer in which a little hand was moving on the screen. I don’t think I was able to explain what it was; my report most likely created the impression of a magic trick. And I didn’t even have the proper lingo: mouse and click were unknown of then, and had I even used them, my father would not have understood what they were without seeing the thing. I think Corrado was among the very first to own a Macintosh in Italy. I am still wondering where he’d found it, since it certainly wasn’t available in stores. It was at his home again that I discovered virtual screens, or even two different screens connected to one computer. If one wanted to keep up-to-date, one only had to visit Corrado at home. Never technology for its own sake, though, in his home it was always put to service to science and art. Submerged by books, papers, articles and technological inventions, Boehm would offer me his thinking on “normal forms”. Those were “combinators” who, once they had exhausted their transforming capabilities, took on a final frozen form, but then woke up and took to transforming again, once they came in contact with other normal forms. Corrado was utterly obsessed by normal forms, which were in his mind not only calculation models, but entities capable of modeling, metaphorically or literally, DNA and life itself. The key was self-application, exactly as it happens with DNA. A lifeless being, a normal form, woke up to life as soon as it came in contact with a copy of itself. Not all normal forms had this miraculous quality, though, and we were tasked with finding the right ones, as if we were synthesizing proteins. There were some who were able to evolve into a double natured form, and switch back and forth between the two forms, like the so-called FormicaLeone (=Ant-Lion) (the title of an article with Benedetto Intrigila). Others could generate on their own all other combinators. Still others would exhibit a polymorphous capability: in some contexts they fulfilled a certain role (for example they would multiply numbers) and in others another role (composing functions). Corrado moved among normal forms as a full-blown “hacker”. It was him who taught me that all possible programs could be generated based on just the addition, multiplication, zero, one and couple combinators. And it wasn’t just theory: Corrado could explain how to actually do it efficiently with all the tricks of the trade, just as a good mechanic would do in his shop. All of this, though, remained for years on paper and blackboard only. It was with the introduction of the “CUCH machine” that combinators’ science and technology started, in Corrado’s hands, to go hand in hand. I never really understood what the CUCH machine was. I only know that from a certain point in time on, Corrado would never be separated from it. He kept it in his breast-pocket and took it out at all times to perform his experiments on normal forms. He spoke about it with such respect that one was under the impression he considered it an oracle. If something went amiss, one could not make out wether it was the combinators’ or the CUCH machine’s fault. The scientific and technological aspects started to merge until they were almost one and the same. I remember a formal occasion, a dinner in his honor: Corrado was entertaining his guests with his CUCH machine. All at once the unpredictable happened. Between a plate of spaghetti and a glass of wine, the combinators were behaving on the screen, replicating or annihilating as they were supposed to, but at the crux of the demo, the batteries of the CUCH machine ran out. Most other people would have given up on completing the experiment, and would have concentrated on the arrival of the involtini, but not Corrado, who, as usual organised, took some spare batteries out of another pocket and continued his demo.