PSI'01, the 4th in the series of international conferences "PERSPECTIVES OF SYSTEM INFORMATICS" devoted to the memory of late professor Andrei Ershov (1931-1988), took place in Novosibirsk Akademgorodok from July 2 to July 6, 2001. The conference was organized by the A.P. Ershov Institute of System Informatics of the Siberian Division of the Russian Academy of Sciences, Alexander Marchuk, director of this institute, was the conference chair and Natalya Cheremnyh was the conference secretary.

Akademgorodok (Academic town) is a big research center, 30 km South from Novosibirsk, the largest city of Siberia. Akademgorodok is located in a picturesque place near the Ob lake. It is surrounded with birch and pine forests and pleasant not only for work but for recreation as well. Silence, beautiful landscape, and pure air are the factors promoting scientific activity and creativity. One can obtain more information about Akademgorodok on the web site http://www.nsc.ru/other/akadem/index.htm

Andrei Ershov was one of the early Russian pioneers in the field of theoretical and systems programming, a founder of the Siberian School of Computer Science. He came to Akademgorodok in 1959 and lived there until his premature death. In 1974 he was nominated as a Distinguished Fellow of the British Computer Society. In 1981 he received the Silver Core Award for services rendered to IFIP. Andrei Ershov's brilliant speeches were always in the focus of public attention. Especially notable was his lecture on "Aesthetic and human factor in programming" presented at the AFIPS Spring Joint Computer Conference in 1972. Andrei Ershov was not only an extremely gifted scientist, teacher and fighter for his ideas, but also a bright and many-sided personality. He wrote poetry, translated the works of R.Kipling and other English poets, and enjoyed playing guitar and singing. Everyone who had the pleasure of knowing Andrei Ershov and working with him will always remember his great vision, eminent achievements, and generous friendship.

The first three Andrei Ershov conferences were held in Akademgorodok in May 1991, June 1996, and July 1999, respectively, and proved to be big international events. The program of the fourth conference included many of the topics of the third one: theoretical computer science, programming methodology, and new information technologies, which are the most important constituents of system informatics. The style of the previous conferences was preserved to a certain extent: a considerable number of invited papers in addition to contributed papers.

The international Programme Committee consisted of 41 members from 17 countries. It was co-chaired by Manfred Broy (Germany), Dines Bjorner (Denmark) and Alexandre Zamulin (Russia).

This time 73 papers were submitted to the conference by researchers from 19 countries. Each paper was reviewed by three experts, at least two of them from the same or closely related discipline as the authors. The reviewers generally provided high quality assessment of the papers and often gave extensive comments to the authors for the possible improvement of the presentation. As a result, the program committee selected 25 high quality papers as regular talks and 22 papers as short talks.

To celebrate the 70th anniversary of Andrei Ershov, a special memorial session was organized. It includes two invited talks, informal communications, and a slide show. The first invited talk titled "A.P. Ershov - a Pioneer and Leader of Programming in Russia" was given by Igor Pottosin (Novosibirsk) who worked side by side with Andrei Ershov for many years. He told the audience of the main steps of Andrei Ershov scientific biography and his influence on the development of informatics in Russia. The second talk titled "A.A. Lyapunov and A.P. Ershov in the Theory of Program Schemes and the Development of Its Logic Concepts" was given by Rimma Podlovchenko (Moscow). She surveyed the contributions of Andrei Ershov in the theory of program schemata and other branches of theoretical computer science.

A broad range of hot topics in system informatics were covered by the following invited talks:

1. Yuri Gurevich (Microsoft Research, USA). The Abstract State Machine Paradigm: What is In and What is Out?
2. Jan Friso Groote, Hans Zantema (Eindhoven, The Netherlands). Resolution and Binary Decision Diagrams Cannot Simulate Each Other Polynomially.
3. Peter D. Mosses (Aarhus, Denmark). What Use is Formal Semantics?
4. Egidio Astesiano, Maura Cerioli, Gianna Reggio (Genova, Italy). From ADT to UML-Like Modelling.

The whole number of participants was 107 with the following distribution by countries:

Russia: 63, Germany: 10, France: 7, Italy: 4, the Netherlands: 4, USA: 3, Denmark: 2, Japan: 2, South Korea: 2, Sweden: 2, UK: 2, Austria: 1, Belgium: 1, China: 1, Estonia: 1, Latvia: 1, Ukraine: 1.

Conference program consisted of fifteen sessions: COMPUTING AND ALGORITHMS, LOGICAL METHODS, VERIFICATION, PROGRAM TRANSFORMATION AND SYNTHESES, SEMANTICS AND TYPES, PROSESSES AND CONCURRENCY, UML SPECIFICATIONS, PETRI NETS, TESTING, SOFTWARE CONSTRUCTION, DATA&KNOWLEDGE BASES, LOGIC PROGRAMMING, CONSTRAINT PROGRAMMING, PROGRAM ANALYSIS, LANGUAGE IMPLEMENTATION.

The participants stayed at the hotel "Zolotaya Dolina" (Golden Valley) situated in the center of Akademgorodok. All conference sessions were held in the Small Hall of the House of Scientists located up the street from the hotel - approximately a five minute walk.

Breakfast was served in the hotel restaurant. Lunch was offered in the restaurant of the House of Scientists. The guests enjoyed traditional Russian cuisine, including famous borshch. During coffee breaks various choices of sandwiches and Russian pirozhki were available.

The welcome party took place the first day of the conference after the memorial session in the restaurant of the House of Scientists. It lasted till midnight. A pianist and a good collection of discs provided a wonderful environment for dances.

An excursion to the Museum of the Cultural History of Siberian and Far East Peoples took place on Tuesday night, directly after the last session. It was followed by an informal picnic at a beach of the Ob lake. The participants enjoyed wine, snacks, and night swimming in the lake.

A barbecue picnic with Russian steam bath took place on Wednesday afternoon, July 4, at the Blue Lake villa, 10 km away from Akademgorodok. It lasted till 10 p.m. People tasted a good Moldavian wine and Russian shashlyk (shish-kebab) and enjoyed taking the Russian steam bath and swimming in Blue Lake.

An excursion to the Geological Museum was organized in the evening of Thursday, July 5. The participants had a chance to see a wonderful collection of Siberian minerals and treasure stones.

The conference dinner took place in the night of Friday, July 6, in the restaurant of the Zolotaya Dolina hotel. In the first part of the dinner there were plenty of speeches following "go to" procedure (each speaker designated the next speaker). In the second part of the dinner people mainly danced to the accompaniment of a music band. The dinner finished at 1 a.m. Many people went to the beach after it where they swam in the warm water of the Ob lake.

PSI'01 was a very well organized high-level conference. The last day the participants thanked the organizers for the good organization of the conference and expressed their desire to come to Akademgorodok once again.

You can find pictures made in the conference at http://psi.nsc.ru/psi01/picture.