Corrado Böhm#

Some thoughts, quotes, anecdotes by his friends, former students, family members ...#

Ever since my first meeting with Corrado Böhm I was fascinated by his creativity, passion and curiosity in doing research.

Corrado Böhm is a great teacher: he takes his students sweetly by hand and shows them how beautiful the world of scientific investigation is. No doubt I have been very privileged in being his student and I feel infinitely grateful to him.

Corrado Boehm's achievements are remarkable as he has both technological results (e.g. showing the practical possibility of a compiler that can compile the language in which it is written, thus leading to the bootstrap of increasing efficiency of computers) and theoretical results (e.g. comparable to the purity of number theory: the separability of beta-eta-normal lambda terms).

...he combines outstanding technical ability and originality of thought with great personal charm, which is very unusual in gifted problem-solvers of this high level.

Roger’s wife, Carol, adds: “he has such charm that things just happen around him...”

I first met Corrado Bohm while I still was a student of physics at the University of Rome, in 1964. The title of his course (the only computer science course at that time) was 'Programming Techniques' but it essentially consisted in a computability course: Turing machines, lambda calculus, Markov algorithms.

A whole new world was disclosed to me. A few months later Corrado was sitting in my parents' house discussing possible topics of my Master thesis: twisting a paper Moebius strip in front of my eyes (and in front of the astonished eyes of my mother!) he was explaining me how the Moebius strip could capture the concept of recursion. My first years of work under his guidance at the Italian National Research Council have been for me a continuous discovery of new problems, new clever algorithmic techniques, new computing paradigms, following the unique light of his inexhaustible mathematical curiosity. To learn the foundations of computer science through his eyes has been a wonderful experience. Many thanks, Corrado!

a significant and fun thought ...

Corrado’s lessons were completely different from any other Mathematics lesson I was then following at the “Sapienza” University. Corrado’s method was similar to the one some swimming coaches apply, who simply throw you into the swimming pool, and then … well, we’ll see. Much the same, he would plunge us without any theoretical preamble into a world peopled by strange creatures, whom he would call “combinators” and whom he introduced to us one by one, making them act on the blackboard as if they were alive.

Little by little we started making friends with K,S,I,C,C*,W,D,A,B,Y &co. without any idea about the status these objects had, or what limits there were to the freedom of creating new ones, learning however to handle them to perfection, precisely the way a child learns addition and multiplication without knowing what a number is. Was it a theory? A programming language? Nothing of sort. In Corrado’s mind, the combinators simply acted, like microbes, say, and the only reasonable approach was that of trying to use them to one’s ends, without posing any limitation whatsoever. I was used to the rigid scheme of traditional teaching, and was expecting, as starters, axioms, definitions, and theorems, but such expectations didn’t match Corrado’s methods. To him research was deeply entangled with freedom, experimenting, art, and fantasy. When he realised I was expecting rules and discipline, he prompted me, somehow challenging me, but being deeply sincere, to NOT read and NOT study, because that would have stifled my fantasy. At that time I was baffled, but after many years I realise now that I got to know combinators much better than I would have, had I studied the various theorems with discipline and in the right order, and I know this feeling is widely shared among Corrado’s students.

and an anecdote ...

When I was a student, Corrado once gave me a problem to solve – I don’t remember exactly now what it was about, maybe I had to find some lambda-terms, or maybe a new list system. I struggled a lot and finally came up with a solution. I immediately informed Corrado and he was very happy. Proud as I was, I wanted to talk more about it, and the following day I got the opportunity to do so, when Corrado invited me to do some work at his home. However, when I managed to bring up the subject in the discussion, he hastily dimissed me by saying that the problem had already been solved. I was taken aback, disappointed: “Why – I thought - why has he given me that problem to solve if the solution was already available? “ Still completely absorbed in his thoughts, he continued: “Yes, it was solved by… by…, oh yes, by you!” Having got to know him, I knew I shouldn’t take offence: his topmost priority was the progress of Science, and, without hesitation or distraction, he was just eager to go beyond whatever he knew was known already, be it so only since the day before.

and more thoughts from Alessandro

I think we don’t know him well, he carries within himself news we cannot predict....

He’s an astonishing creature because he walks the world in a way that is both natural and sweet, and he will always surprise us because he’s spontaneous and never banal. I feel it is a privilege to be his wife and to have been able to live with him.

I am the firstborn of a genius… of a father of information technology, … and I want to remember here some of the traits of the personality of Corrado Böhm that haven’t been talked about elsewhere.

Corrado was called “Corrodi” within the family, ever since a janitor, at the Swiss University where my father was undergoing his Ph.D. examinations, addressed my mother, who was anxiously waiting for him outside, calling him “Doktor Corrodi”.

Corrodi always loved “double face” objects, I remember a raincoat/overcoat … and I’ll say, in the teeth of pure mathematicians, he seems to me to have found the same double-ness in the quintessential undecidable nature of numbers who can be both operators and operands at the same time!

Corrado always considered all games as algorithms, and once, when he had beaten me at checkers one more time, and I had lost it, and had thrown board and pawns out of the window, he immediately went downstairs to recover them, searching for every piece with a monk-like patience … and when one day I asked him for an Apple II, he had me show that I knew how to write a program to play tic tac toe… and when, for a long time, I went on begging all day long for a Lisa, he would answer: “No, you must wait for the Macintosh”…

Corrado always fought against dogmatic good-sense, so that the Socratic/Psychoanalytic “know yourself” became “recognize yourself” … whence the compiler and the lambda calculus; … to the mechanic Marxian juxtaposition Structure/Supra-structure, he countered the terrific unifying hypothesis of “Natural Selection” … hence also his latest taking to Bioinformatics, “which couldn’t care less whether a problem is NP” and solves it in an approximate, self-organised and parallel way… Corrodi is Great!



I am honored to write something about Corrado, on the day of his 87th birthday --it never happened to me before. Since I was little I was very fascinated with the way Corrado related to any kind of what would now be called technological gadgets and gizmos. He taught me to use the slide rule but also Kurta, a coffee grinder shaped mechanical calculator. I remember also going to Forte Antenne to listen to my dad using his CB radio to talk to people around Europe and even on the top of the Monti Cimini at 1000m altitude to reach further around the world with his CB radio (the so called "baracchino"). When the time came I believe in 1972 when he wrote a sequence of instructions to be used on the Sanyo Elsi Mini pocket calculator with red digits to compute the square root even though only the four operations were possible, I exulted. Also accompanying him to the Computer Science Institute in Turin and seeing the PDP 11 being booted with a sequence of buttons in the front panel is pretty well engraved in my memory. Several years later taking part to his University lectures as a student was also an enriching experience (because until then I knew him as a father in the family interactions) that revealed to me different aspects of his personality. It allowed me to see how original and innovative he was compared to all the other professors I encountered in my university training. I am pretty sure that he never repeated a lecture twice in different years of his teaching of "theory and applications of computing machines". I think he had the ability of "naturally selecting" the best students by sparking their interest in the subject during the course of each lecture.

Ever since I was a child I have always felt, and experienced, that no matter how busy my father was with his brilliant discoveries, his mind many feet above the ground, he was always within my reach.

When I needed him, were it for a childish trifle, or something more important, Dad would grant me all the time and attention needed, regardless of the importance of the issue I raised, and this made me obviously feel at the centre of his life. And I thank him for that... Could this be the reason why I can’t stand people who cannot listen?

more thoughts by friends ...

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