### Developers Club geek daily blog

2 years, 10 months ago

#### Birthday, on January 10, 78 years

Couple of examples of congratulations of Donald Cnut happy birthday last years

#### Patents

"Nobody can "own" a mathematical formula. The mathematics belongs to God."

Donald Cnut,

#### Religion

Book Things a Computer Scientist Rarely Talks About

Lecture in Google: Interaction between belief and science

#### Fun

The whip entered the instrumentation system.
[source]

#### Music

Every day brings new proofs to the fact that concepts of information science are applicable to the spheres of life having very remote or not having any relation to computers. The purpose of this review – to show how important properties of popular songs are best understood in terms of the modern computational complexity theory.

It is known that almost all songs of length of n need the text of length ~ to n. It, however, imposes considerable requirements to the volume of your memory if it is necessary to study a set of songs; therefore our ancient ancestors invented concept of a refrain [14]. When the song has a refrain, as shown in the following lemma, its complexity of storing can be reduced to cn where c <1.

Lemma 1

Let S – the song containing m of couplets of length of V and a refrain of length of R which is sung at the beginning, in the end and between the next couplets. Then complexity of storing of the song S makes (V / (V + R)) n + O(1) for fixed by V and R at m → ∞.

Continuation here.

#### Russian

I would learn Russian only for the fact that it Yershov talked.

"It began still when I was a student of a last year. Then there was only Andrey's book "Programming for high-speed electronic computer", and we, group of students, could convince the teacher of Russian to include it in a course as one of two collections of texts for studying of scientific lexicon."

In "honourable users" of own publishing system and its Cyrillic version Donald Cnut was accepted in May, 1994 when by the invitation of the St. Petersburg university visited St. Petersburg for receipt of a rank of the doctor of honoris causa of St.Petersburg State University

Cyrillics was the first not roman type which appeared in Tekh'E. By the way, Cnut knows Russian — he learned it to read works of Yershov in the original.

Donald Cnut's memories of Andrey Yershov
Andrey Yershov on the conferences Algorythms in Modern Mathematics and Computer Science, USSR, Urgench, 1979 Editors asked me to write some of my personal memories of Andrey Yershov. Though we with Andrey lived on the different ends of Earth and we were separated by nearly 12 time zones, his life exerted considerable positive impact on mine.

It began still when I was a student of a last year of Case Institute of Technology institute. Then there was only Andrey's book "Programming for high-speed electronic computer", and we, group of students, could convince the teacher of Russian to include it in a course as one of two collections of texts for studying of scientific lexicon. For us it was remarkable experience as many technical computer terms could not be found in our dictionaries, and even the teacher did not hear earlier some of them at all! (The transfer into English executed by Nedler then was not published yet.) We felt that we see "this" Russian in that type in what it is really used in science; the book made on us much stronger impression, than the second text in which it was told about satellites and research of space, but at very primitive level.

This book not only helped me to master Russian better; from it I learned interesting algorithms of optimization of the compiler. Actually early work of Andrey which was an incitement to creation of this important field of computer science still causes interest. Its method of a material statement also was very significant: I used afterwards the flowcharts presented for the first time in its book for an illustration of process of execution of the program in the article Computer-drawn flow charts ("The flowcharts constructed by the computer") issued in Communications of the ACM, September, 1963, p. 555-563) and the subsequent series of books "Programming Art".

The first personal meeting happened to Andrey at conference of the working group of IFIP where the successor to the Algol-60 language prepared. By then I learned that Andrey irrespective of Gene Amdal invented hashing with linear number of tests — important algorithm which studying became a turning point of my life as brought me into the area of the algorithmic analysis. (See a footnote on p. 529 in my book Sorting and Searching ("Sorting and search"); this footnote is in Russian translation on p. 628). I had heard a lot about the new methods which are a part of the project of the Alpha language which was conducted by Andrey. Therefore I was extremely glad to an opportunity to meet it personally especially as as it became clear, he is fluent in English. We spoke about two hours about compilers and languages while it copied on the copier numerous documents for this conference.

Afterwards we could is more often see it as it regularly came to meetings with John McCarthy in Stanford University. One of such visits became the prime cause, perhaps, the most memorable for me an event — mine

participations in the Algorythms in Modern Mathematics and Computer Science conference ("Algorithms in modern mathematics and computer science") which took place in the USSR in Urgench in 1979. This conference — pilgrimage of scientists to the holy sites, to the birthplace of the concept "algorithm" — for me was the dream which became a reality. Though we with Andrey officially were registered as cochairmen of conference, actually Andrey undertook 99% of work while I could have a rest and enjoy the events, learning a set important from people whom he met here. It happens time in life, and I hope that many scientists working in the field of computer sciences will be able to participate in a similar meeting if someone is inspired by Andrey's example. For this week I knew it much more better and was especially struck that, how brilliantly it coped with all numerous roles: head of conference, organizer, philosopher, speaker, translator and editor.

I have many other memories including about a remarkable case when we with the wife met Andrey on evening of the American quadrille and it performed Virginia Reel and "to - si - to", but what is already told, quite enough, to understand how important role in my life was played by Andrey.

During its last visit to Stanford I learned about enormous work which it conducted in the last years of life, about revolutionary changes in teaching computer sciences to millions of students what with delight spoke around the world about. All of us grieve over what Andrey's lives was foreordained to end so soon, we admire that much that it managed to it to make, and we know that fruits of his life will become a source of knowledge for the next generations of the scientists of the whole world working in the field of computer sciences.

#### Sources

Habr — Donald Cnut
Computerra — Who you are, professor Donald Cnut?
Elements — Donald Cnut
Wiki — Cnut, Donald Ervin

P.S.
Assignment and sense of this image remains to unknown so far
photo