Dines Bjørner

1. A Personal Assessment

Andrei spanned many professional disciplines: Compiler Technology, Theoretical Computer Science, Partial Evaluation and Mixed Computation, Computer Literacy and School Informatics. To me Andrei was a true scholar in the field of Computation Sciences. There are perhaps only a handful such scholars worldwide. To me Andrei was the first and foremost, if not the only, Computation Science Academician in the entire USSR Academy of Informatics Sciences. Only he understood fully and deeply the true nature of the Computation Sciences. His much too early demise poses a serious problem for the proper future direction of Soviet science in the area of the Computation Sciences. As I see it, the USSR are world masters in Control Theory, Mathematical Modelling and Optimization — but these fields relate to the Computation Sciences as does the glove to the hand. Without a hand there is, in the modern age of informatics, no need for the glove.

May the life and inspiration brought to all of us by Andrei Ershov be a reminder of the central, crucial importance of the Computation Sciences and their proper role on the family of sciences.

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In this eulogy I will henceforth concentrate on reminiscing about Andrei and our encounters over the last decade. I can, obviously, only touch upon those facets of Andrei's rich life which I witnessed. Many other scientists can vouch for an even richer fabric.

2. Andrei Ershov, the Internationalist

Few Soviet scientists have tra­velled as widely and often as did Andrei. He was welcome everywhere he went: in every country in Europe, in the US, and had time permitted, incre­asingly so in China and Japan. I just came home from a 11 day trip in Sep­tember this year to Japan and China. Many scientists in both countries re­membered with joy memorable times with Andrei, and were saddened by his early departure.

Over the years I have met Andrei outside the USSR in: Tokyo, Melbour­ne, Strebske Pleso (CSSR), Capri (Italy), Paris, Munich, Sofia (Bulgaria), and, of course, Copenhagen. Always professionally active, alert, communi­cative and inspiring. In Tokyo and Paris, at IFIP World Congresses, he would, in addition to own work, present that of his fellow Soviet scientists who were not able to attend these congresses — and few, if any, would present others' work so diligently. At times I believe his presentations to surpass those of their authors! So transparent, so didactically resolved.

His ability to engage his fellow peers in deep scientific discussions were legendary: with F. L. Bauer in Melbourne (1980) and Munich (1986), with S.Eilenberg and H. Rasiowa in Strebske Pleso (1981), with Joseph Goguen, Ugo Montanari, Peter Wegner and William Wulf on Capri (1982), and with Seymour Papert and Blagovest Sendov in Sofia (1987). With the founding, formalizing and experimental trio of the sub-field of Partial Evaluation and Mixed Computation: Yoshihiko Futamura, Andrei Ershov and Neil D. Jo­nes, these cross-fertilizing encounters reached, I believe, a latest high point.

3. Andrei Ershov, the Humanist

Andrei's concern for the humanisation of the results and possibilities of the computation sciences is well worth remembering. From the impressive scientific basis of deep, deep insight into the mathematical foundations of the computation sciences, sprang a didacti­cally and pedagogically transparent manner of explaining the practical im­ports of the computation sciences. This clasification was translated, by An­drei, into not only outstanding publications, notably the Lausanne World Conference on Computer Education "Computer Literacy" paper, but also into one of the most massive programs for bringing a whole generation of school children into Informatics: the USSR programme, which Andrei succesfully, already marked by his final illness, reported on in Sofia (1987).

On my travel with Andrei, through Slovakia, to the Strebske Pleso MFCS'81 conference, I noted his relentless questioning, of our hosts, concer­ning local Folk traditions, their survival and future possibilities. Andrei specifically asked me to take a photo of him. up against a wooden church, next to a Madonna sculpture.

His editorship of the Soviet journal Programming', I recently had oc­casion to discover, also allowed, him to edit (hence publish) other Soviet scientists' worthwhile technical/scientific papers — papers of a nature quite common in for example English and US journals, but, for lack of deep ma­thematical models otherwise not acceptable in a Soviet journal. His concern for the aspiring science and struggling scientists was thus also a witness to his deep human concerns.

4. Andrei Ershov — his University Study

It was at a dinner we had to­gether, the two of us, in Tokyo, in 1980, at the historical Kyoto cusine of the Minokichi restaurant, that Andrei told me the following story, which explains one facet of how he became involved in the Computation Sciences.

Andrei seemed to have lived, for a while, with his parents, in a part of the USSR which, for a.time was occupied by the German forces in the Great Patriotic War. At Moscow university, years later, he applied to study theo­retical physics. Together with several other top candidates permission was denied. The group wrote Stalin, to ask why, with the result that one of Stalin's personal secretaries quite soon afterwards met them and explained that for the above (War) reason, and for reasons of state security, they were free to choose any other study. Andrei chose the emerging Science of Compu­tation. And, I believe, we shall be most grateful for that!

5. Andrei Ershov, my Mentor and Friend

I first met Andrei in Novosi­birsk in September 1978. On the basis of some reformulation, of mine, of his Brunswick (IFIP TC2 Conference) paper on Mixed Computation, I had been allowed to visit him and his group en route home from a Kyoto IFIP WG2.2 meeting. I had occasion to revisit him in Novosibirsk in 1980 (en route to the Tokyo IFIP World Congress — IFIP'80), and in 1986. Our walks in the wonderful Golden Valley forest, and our lunches in the Academy vil­la — with always intensive, wideranging discussions — gave me much to think about.

My grandfather travelled widely in Russia and White Russia, in the pe­riod 1902—1917, with one visit thereafter: 1936. Many letters to his seven children from the pre-revolution period were published in many Danish lan­guage newspapers, and later in a book (1937). I gave Andrei Ershov a copy of this (Danish language) book shortly after our Tokyo dinner. Those letters and that book is a testimony to my grandfathers deep affection for the Rus­sian people. I am fortunate, through Andrei Ershov, to have continued that deep affection.

It was at the IFIP TC2 Working Conference on Program Specification and Transformation in Bad Tolz, near Munich, in April 1986, that Andrei charged me with organizing, in Denmark, an IFIP TC2 Working Conference on Partial Evaluation and Mixed Computation. Andrei was already marked with his terminal decease, but, as always, full of energy, plans and hope for the future. The conference, held in October 1987, on the lovely Danish pe­ninsula of Gl. Avernaes, became a tremendous success. Not because of my organisational skills. No, but primarily because of Andrei Ershov's abilities: to lead a delegation of 7 soviet scientists, to focus all the discussions, and to attract, to this conference, many international scientists: prof. John McCarthy, dr. Y. Fuiamura, prof. Neil D. Jones — to mention but a few.

This conference was Andrei Ershov's crowning achievement: here he was recognized as the forceful, stabilizing founder of one of the most exciting new fields of the Computation Sciences: that of Partial Evaluation and Mi­xed Computation. The North-Holland Proceedings is a lasting testimony to his work. The conference was also a first, I believe, in bringing a number of Soviet scientists into a very productive, close working relation with many international scientists — to a relatively «smallish» event so many Soviet scientists. That boded well for the future of the international community of science and scientists. Also this was Ershov's achievement. I am grateful to Ershov for having allowed me to organize this conference.

My last encounter with Andrei was on the last Saturday of May 1988. My wife and I had been guests of the USSR Academy of Sciences, invited by Ershov, and were visiting Moscow, Riga, Tallinn and Leningrad. Andrei was undergoing medical treatments in Novosibirsk and only came to Moscow after our departure from there. On a Friday evening, in Leningrad, 2 nights before our departure, Andrei phoned, from Moscow, announcing his arrival, next morning, by train, in Leningrad! We spent a lovely, lovely full day together. In our car we visited the Peter and Paul Fortress, the Summer (Petrodvorets), Pushkin and Pavlovsk Palaces. Andrei was running hither and dither, securing tickets in front of all queues, making sure my wife and I heard the noon-day gun salute, and saw the fountains of the palaces, and many other things.

6. Benedictum

That day, Saturday, 29 May 1988, was the crowning me­mory of many encounters with a lovely man — a man for all seasons, a man blessed by a full life. May we all take him as an example — his life was, was to me, in honour of God. May his life and struggles never cease to have im­pact on Soviet, as it has had on world, Computation Sciences: on its practi­tioners that they push their students in front of them, inspiring and inter­nationalizing them, and on the societal emphasis on the Computation Scien­ces in their own right.

Bjørner D., Prof., Member Danish Acad, for Techn. Sciences

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