Grzegorz Rozenberg - A Magical Scientist and Brother#

Arto Salomaa
Excerpt from:
Natural Computing Series
Algorithmic Bioprocesses
10.1007/978-3-540-88869-7_1
Anne Condon, David Harel, Joost N. Kok, Arto Salomaa and Erik Winfree

1 General#

This is a personal description of Grzegorz Rozenberg. To justify the word brother appearing in the title I quote Grzegorz from [6] where he describes his "wonderful family". Then I have two brothers of choice, Andrzej and Arto. It is difficult to imagine better brothers (an interesting aspect of this brotherhood is that Andrzej and Arto have never met).

There is something magical in the fact that one man, Grzegorz, has been able to obtain so many and so good results in so numerous and diverse areas of science. This is why I have called him a "magical scientist". He is also a very interdisciplinary scientist. In some sense this is due already to his educational background. His first degree was an Engineer in electronics, the second a Master in computer science, and the third a Ph.D. in mathematics. However, in the case of Grzegorz, the main drive for new disciplines comes from his tireless search for new openings in basic science, rather than following known tracks. Starting with fundamental automata and language theory, he soon extended his realm to biologically motivated developmental languages, and further to concurrency, Petri nets and graph grammars. During the past decade his main focus has been on natural computing, a term coined by Grzegorz himself to mean either computing taking place in nature or human-designed computing inspired by nature.

Everyone who has worked with or otherwise followed closely Grzegorz Rozenberg has been profoundly impressed by his overwhelming enthusiasm in doing research. One can do great science and have fun doing it is one of his thoughts often expressed. Grzegorz has contemplated thoroughly the qualities of good science, and is ready to discuss and give advice about questions such as the choice of your research area or topic, what is important and what is not, or what is applicable and what is not. Sometimes a widely investigated research area begins to stagnate. Research in such an area moves into side tracks and eventually dies out. Often an invigorating new idea, perhaps from a different field of science, changes the situation. These and related thoughts usually come up in discussions with Grzegorz. While some science writers talk about the "end of science", meaning that one already has walked through all significant roads, Grzegorz has quite an opposite view: we are in many respects only at the beginning of the road. In particular, this is true of computer science and natural computing. I will next outline some of Grzegorz's thoughts about these areas.

Computer science develops tools needed for ICT, Information and Communication Technology. Such tools include computer networks and software methodologies, the theoretical basis being essential. Computer science is more than ICT, it is the the general science of information and information processing. The European term informatics is much better than computer science. The former term does not refer to any device or instrument for information processing. Such instruments always presuppose a paradigm of thinking about information processing, whereas if one speaks of "informatics", no devices or paradigms are stipulated.

In particular, informatics should study computing and information processing taking place in nature, and develop paradigms based on it. Research in natural computing, as Grzegorz understands it, is genuinely interdisciplinary and bridges informatics to natural sciences. Evolutionary computing and neural computing are older examples of such bridges. Human-designed computing inspired by nature includes such paradigms as molecular computing and quantum computing.

This is no place to overview Grzegorz's huge scientific production (hundreds of papers, some eighty books or edited books), or to discuss his contributions to the scientific community. (For instance, he has been EATCS President much longer than anyone else, not the mention his more than twenty years as the editor of the EATCS Bulletin.) I will still return to our scientific cooperation in terms of three glimpses of it, in Sections 4-6. Next I will discuss other matters.

2 Grzegorz and Bolgani#

You get a good picture about Grzegorz as a human being by reading [6]: what is important for him, what he likes to do, where he has been and whom he has been with. He has surely had a many-faceted, even adventurous life, centered around family (most importantly Maja and Daniel), science and also magic. Before I add some personal comments to the matters in [6], I mention a couple of things, covered very little or not at all in [6].

The life changed for Grzegorz when the grandson Mundo came to the world in August 2005. After that much of his conversation has consisted of telling about recent happenings with Mundo. Our email has piles of pictures of Mundo. I have a big picture of Grzegorz and myself, standing in snow during a sauna intermission in 1980. It has the text Happiness is being a Grandfather. I am glad that this is now true also for Grzegorz.

Owls are briefly mentioned in [6]. By now Grzegorz has a huge collection of owl figurines, real stuffed owls and material dealing with owls. This exhibition is a real wonder to a visitor in Bilthoven. Grzegorz calls owls magicians of nature. His interest in owls was initiated by some pictures taken by Juhani Karhumäki in the 70's.

Also Hieronymus Bosch is only briefly mentioned in [6]. During the past decade, Grzegorz has become a real expert on Bosch. He has a comprehensive library of books on Bosch, in numerous languages. I was sorry to tell him that I have found no such book in Finnish. Grzegorz likes to go to "boschian" lectures and meetings. My favorite Bosch cite is



I do not know whether Grzegorz has seen it or likes it.

I will tell at the beginning of the next section about my first meeting with Grzegorz. Some years after that Grzegorz started to visit Turku. In 1976, one purpose of the visit was the Ph.D. defense of Juhani Karhumäki. Grzegorz has had many excellent Ph.D. students of his own, and has been an external examiner or opponent in many other Ph.D. defenses. The reaction of the candidates has been overwhelmingly positive. How helpful, constructive and friendly he has been, can be seen from many contributions to [1].

Grzegorz stayed with my family many times in the 70's and became famous, among many other things, for eating huge amounts of blueberry pie. I was called "Tarzan", and Grzegorz wanted to become a member of the Tarzan family. We decided that he will be Bolgani. Later on "Bolgani" became his official name as a magician, and it also appears on his visiting card. In the following I will use the two names interchangeably.

Although most of the time a scientist, Bolgani has also periods when he lives with magic. He has developed the performing art of close-up magic to a high professional level. I have been watching him in numerous shows, both in private homes and in conference gatherings. Since long I have not tried any more to explain or understand the illusion, I just enjoy the show. When Bolgani gave a performance in my home, one of the guests came later with the \explanation" that he was wearing contact lenses of a special type. Illusions have no explana- tion.

Undoubtedly Bolgani is a born magician. The maiden name of his mother is Zauberman. The name of his wife Maja means "illusion" in Hindu. His hands are very sensitive, I have not seen anyone handling a deck of cards as gently as Bolgani.

A magician likes to give a performance. Grzegorz is a great lecturer. The community knows this: all the time he has numerous invitations. It is di±cult to match his sense of humor, and probably impossible to match his capability to include magical illusions in his lectures. Many people make easy things dif- ¯cult in their lectures. Grzegorz has the talent of making di±cult things easy. As Maurice Nivat has said, Grzegorz is always enthusiastic, always optimistic, always amusing and never boring.

Bolgani often presents a sequence of illusions within the framework of a story, such as the following. Bolgani explains that in Chinese the names of the suits hung tao (heart) and hei tao (spade) are similar, and therefore some confusions may rise. But now we try to be careful. He then shows the audience some hearts and puts them on the table, as well as some spades and puts them also on the table, far from the hearts. "So this pile is hung tao?" The audience agrees. "And this is hei tao?" Again consensus. Bolgani then entertains the audience and talks about various matters. About owls. About sauna. That laughter, and for him nowadays Mundo, is the best medicine. That one should never assume anything. That the only place where success comes before work is dictionary. Then Bolgani goes back to the cards. "So this is hung tao and this hei tao?" General agreement. But when he shows the cards, it is the other way round. "Too bad, let us see what happens if we put everybody in the same pile." He puts first the pile of hearts on the table and the spades on their top. Again some entertainment. "Now let us see if they interchanged again." Bolgani picks up the cards and shows them. "This is absolutely crazy. They are all zhao hua (club, grass flower)!"

3 Brother#

Grzegorz had been in Holland about one and half years, and was running a country-wide seminar in Utrecht, where also foreign speakers were invited. I got an invitation (by ordinary mail, not by phone) from G. Rozenberg in May 1971. I was not familiar with the name previously. He waited for me at the airport and arranged our meeting through loudspeakers. He looked much younger than what I had anticipated. He drove a small Volkswagen. We got immediately into a very hectic discussion about parallel rewriting and L systems. This was contrary to all principles about driving, expressed by Grzegorz later. After about one hour I started to wonder why we had not yet arrived in my hotel in Utrecht, well-known for the model railroad upstairs. It turned out that we were still on some side streets of Amsterdam.

The same day Grzegorz told me more about L systems, at the university and during the dinner at an Indonesian restaurant. This turned out to be an area where our scientific cooperation has been most vivid. The most important outcome is the book [7] but L systems play an important role also in 10, 9.

I had four lectures in the seminar, and Grzegorz also arranged a big party in their Marco Pololaan apartment. Although the twenty people present were quite noisy, the baby Daniel slept all the time. There I got to know many of my friends the first time, notably Aristid Lindenmayer. L systems seemed to be a really fresh idea. I got carried away, and already decided to include a chapter about them in my forthcoming book on formal languages. During the next few weeks I exchanged with Grzegorz numerous letters about the topic.

At this stage I would like to tell two stories about our joint books. In some way they illustrate very well Grzegorz's friendliness, e±ciency and professionalism.

When working on the book [7], we had many specific deadlines, depending on mutual trips etc. Once I got very nervous that Grzegorz was too involved in other research topics, and could not possibly any more make the deadline. I wrote a very angry letter to him. His answer was very brief. "Tarzan has never before written such an angry letter. The reason is simple. In your letter you mention that you did not go to sauna in two days." That was it, and he made the deadline.

In March 1994, Grzegorz suggested to me: "Let us make a handbook on formal languages." We started planning it immediately. In less than three years, a copy of [10] (three volumes, more than 2000 pages, 3.6 kilos altogether, more than 50 authors) was in the library of Turku University. Are there similar examples of such speedy editing of such an extensive handbook-type scientific work?

Very soon Bolgani became a close family member. My wife tells him everything about our cats and often wears blouses given by him as presents. He is a coauthor in my son's first scientific publication. My daughter always liked to travel to Utrecht because "it is the town with the Orange Julius". My grandchil- dren call him Äijä-Bolgani (grandpa-Bolgani). My grandson was very impressed because Bolgani drew lots of coins from his ears, and my granddaughter because of his expanding command of Finnish. On the other hand, Bolgani's late mother treated me as her own son. I myself have, more and more during the years, learned to ask his advice in difficult decisions and situations.

Bolgani always brings carefully selected gifts, not only to me but also to everybody in my "clan". In 1975 he gave me a very special memory device. It was with me everywhere during thirty years, until it finally wore out. No substitute was available, and I had to be satisfied with miserable alternatives. But in 2007 Bolgani gave me a substitute, even better than the original!

My brother has an immense supply of jokes and anecdotes, always suitable to the occasion. Often a fatiguing situation entirely changes by his comments. When I came exhausted in the airport bus, together with some other conference participants, to Waterloo in 1977, Bolgani was there to meet us. Instead of greeting me, he went to the driver, pointing towards me: "Did that fellow behave well in the bus?"

Sometimes I have experienced a real surprise. I had forgot my slippers in Bilthoven. The next time I was there they were not found, and Bolgani just remarked that maybe the cleaning lady had somehow misplaced them. Sometime afterwards I was staying in Hermann Maurer's (a close friend of both of us and a marvelous scientific collaborator) house in Graz. When I entered my room, my slippers were there!

Bolgani claims that I have a good memory, whereas he has a bad one. I am not sure of this, it could be the other way round. For instance, in Bolgani's writings to me the expressions "Rabbit Ph.D. Story" and "Dog Paper Story" appear many times. I do not remember what they refer to.

Some of our best times together have been in sauna. Bolgani has a special sauna certificate and many sauna records, for instance, the shortest time between the plane landing and him sitting in sauna, or seeing special animals from the sauna window. Even Aristid Lindenmayer never saw a supikoira (raccoon dog). I let Bolgani himself speak. ("Löyly" is the Finnish word for sauna heat.)

When you come to Tarzan nest
You get sauna at its best
Where you can admire
Löyly and birch wood on fire
A lot of flora and fauna
Can be seen from Salosauna
But with Bolgani and nice weather
You can see two supikoiras together




Quoted from: Natural Computing Series
ISSN: 1619-7127
Book: Algorithmic Bioprocesses
Publisher: Springer Berlin Heidelberg
DOI: 10.1007/978-3-540-88869-7
Copyright: 2009
ISBN: 978-3-540-88868-0 (Print) 978-3-540-88869-7 (Online)
Part: Part 1
DOI 10.1007/978-3-540-88869-7_1



The footnotes refer to the footnotes in the printed article.



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