!!From the Bulletin of EATCS No. 85
!Interview with Professor Grzegorz Rozenberg\\
by __Cris Calude__
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Professor G. Rozenberg visited the University of Auckland as an invited speaker of DLT’04. Professor Rozenberg is well-known to the EATCS Bulletin readership (he was, among others, the President ofthe EATCS for 9 years and the Editor of the EATCS Bulletin for 23 years) so it’s pointless to make any introduction. I just want to mention some numbers: he published about 450 papers, 6 books, and is a (co-)editor of more than 70 books.
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He has kindly answered a few questions related to the topic of his lecture at DLT’04, "Natural Computing".
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__CC__: You are a professor in the Department of Computer Science of Leiden University and an adjoint professor in the Department of Computer Science of University of Colorado at Boulder, the head ofthe Theoretical Computer Science group at Leiden Institute of Advanced Computer Science (LIACS), and the scientific director of Leiden Center for Natural Computing (LCNC). You serve, in various capacities, in 18 editorial boards, and chair quite a number of steering committees. How can you survive?
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__GR__: The only recipe for survival is motivation and (implied by it) DEVOTION RULE which says that one should not take any serious commitment unless one is sure that it can be fulfilled 150%. This gives you a safety margin: in unusually hectic times you can still fulfil your obligations in a satisfactory manner. My motivation comes also from a deep conviction that serving the scientific community is a very noble and satisfying activity.
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__CC__: I did a Google search for "Natural Computing" and got 9,290 hits with ''Kluwer Natural Computing: An International Journal'' and the Leiden Center for Natural Computing on the Hrst three. What is Natural Computing? Did you coin this name? Who are the precursors?
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__GR__: Natural Computing is computing taking place in nature as well as human-designed computing inspired by nature. Research in Natural Computing is genuinely interdisciplinary, and it is concerned with theoretical, experimental, and applied issues, As a matter of fact, Natural Computing forms a “natural" bridge between informatics and natural sciences.
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When I introduced this name more than 20 years ago it was considered to be a sort of science fiction, but by today it became very popular, and the science of natural computing is really flourishing: there are institutes, journals, book series, conferences, professorships, … of/on Natural Computing.
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It is difficult to pinpoint the real precursors of research in Natural Computing, and it is always very difficult to give the just credit (to all involved) in such matters. Here are some names that come to my mind now: A. Turing (his work on morphogenesis and on connectionist models), J. von Neumann (biologically inspired computing), WS. McCulloch and W. Pits (they viewed neurons as computational devices), A. Lindenmayer (he considered development of organisms as computational processes), J. Holland (who noticed that basic features of evolution can be utilised to design algorithms), … - once again, this is an ad-hoc list.
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__CC__: What is more important for research in Natural Computing: potential applications or understanding how "nature" computes? Does "nature" really compute?
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__GR__: Advancing our understanding of computation taking place in nature will often lead to (potential) advance in human—designed computing, simply because so often the way nature computes is superior to the way humans compute. In this sense, the understanding how nature computes is "primary". But there is a catch here. Our classical notion of computation is rooted in the quest for formalising the way humans compute/calculate—it dates back (at least) to the work of Leibniz and it culminated in the first half of the 20th century with the research/results by Post, Church, and Turing, Quite often, this (beautiful) notion/idea of computation does not really apply to the computation going all around us in nature because it violates various "underlying axioms" of the way that nature works. I strongly believe that research in Natural Computing will eventually lead to a (strikingly?) novel notion of computation, as a matter of fact to a new “‘science of computation" which will be developed by interaction/co-operation of computer scientists, biologists, chemists, mathematicians, physicists,   Indeed, the research in Natural Computing has already changed our understanding of what computing is about.
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__CC__: Can you give us examples of such violations of underlying axioms?
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__GR__: This is a dangerous question because an answer to it may (should?) be given by writing a whole series of papers. Let me instead just mention a number of features that underlie models frequently considered in computer science that often/mostly do not hold for computing taking place in biological systems:
*Division into software and hardware.
*Persistence of states: if a (local) state is not processed then it remains unchanged.
*Sequential or moderately parallel mode of operation.
*The computing device (model) realises some kind of input/output function or relation.
*The computing device (model) operates in an environment that is independent of the device itself.
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__CC__: You founded two journals and a book series dedicated to natural computing. Tell us more about them.
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__GR__: The journals are; "Natural Computing”’ by Kluwer and "Theoretical Computer Science, Series C: Theory of Natural Computing" by Elsevier, and the book series is "Natural Computing" by Springer. The "Natural Computing” is a journal of a very broad scope: it covers experimental, applied and theoretical aspects of Natural Computing. You will Hnd there publications by biologists, chemists, nanoscientists, physicists, mathematicians, computer scientists, ... – it really reflects very well the genuinely interdisciplinary nature of Natural Computing. It is an ideal journal for publishing special issues ofinterdisciplinary conferences such as, e.g., "DNA Computing”. The TCSC journal, on the other hand, aims at publishing theoretical papers that are in the style ot` the well established TCS joumal. Then, the book series “‘Natural Computing" by Springer publishes both texts and monographs covering the whole spectrum of "Natural Computing" (theory, experiments, and applications). All three publications are doing very well and will certainly grow and Hourish in the years to come.
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__CC__: Tell us about your engagement in magic and the paintings by Hieronymus Bosch?
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__GR__: This is a very dangerous question because it opens a whole Pandora’s box. Let’s keep it for our next conversation.
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__CC__: Thank you very much for this interview.