DEMONSTRATIO MATHEMATICA Vol. VII No 3 1974

THE ADDRESSES DELIVERED AT TECHNICAL UNIVERSITY OF ON THE 19th JANUARY 1974 DURING THE CEREMONY OF CONFERRING THE DIGNITY OF DOCTOR HONORIS CAUSA UPON EMERITUS ORDINARY PROFESSOR DR STEFAN STRASZEWICZ-

The address of the honorary promoter ordinary Professor dr Edward Otto

The beginning of the 20th century was a period of fluori- shing development of new branches of : theory and . It is true that the main concepts of those dis- ciplines had been introduced in the 19th century by Cantor and Poincaré, but it is only in the 20th century that they were generally accepted and gained influence upon the pro- gress of mathematics. Professor Straszewicz became acquainted with the new ideas in mathematics while studying in Zürich under the famous ma- thematician Zermelo. on his return to Warsaw in 1918, Pro- fessor Streszewicz published his first paper in'the periodical , founded and edited by a group of Warsaw mathematicians. It was a period of lively activity of the Warsaw centre, dominated by Zygmunt Janiszewski, who had worked out a long-term program aiming at an intensification of mathematical research in . The plan was fully implemented, and as early as the thir- ties, owing to the contribution of the so called Warsaw school and to the great achievements of a group of mathematicians inspired by the outstanding mathematical individuality of Ste- fan Banach, working then in Lwów, Polish mathematics became one of the five greatest mathematical powers of the world. Professor Straszewicz, owing to his investigations in topology, found himself, together with our prominent mathema-

- 279 - 2 ticians , , Bronislaw Knaster, and - later - , in the first ranks of our topologists, who played a decisive role in developing the concepts oh that discipline. The value of scientific achievement is usually measured by the durability of its significance for science. This value changes with time. What was most essential in the past may play a more limited role today, giving precedence to other, more up-to-date problems. However, the works of Professor Straszewicz contain many results which have lost nothing of their validity and topical interest. Such is, for example, the paper in which he generalizes and further develops some of Professor Zygmunt Janiszewski's results in plane topology; they still have considerable importance in the theory of par- tial differential quations. The same can be said about another paper - of fundamental importance for hyperbolic geometry. Professor Straszewicz*s scientific output has been highly valued by mathematicians, as is shown by his being offered in 1969 a honorary membership of the Rüish Mathematical Society. Another part of Professor Straszewicz's activities con- cerns education and cultural matters. In the inter-war period he was a member of a Commission qualifying secondary school teachers and in this capacity he was able to do a great deal towards raising the standard of school teaching in our country He was also the author of numerous excellent school textbooks of mathematics, which were used by millions of Polish children throughout many years. His textbooks stimulated the children's thought processes, teaching how to think clearly and how to formulate ideas in a correct and lucid manner. Por nearly 40 years Professor Straszewicz supervised the preparation of school syllabuses of mathematics, devised some of them him- self and collaborated in working out others. He has always been a fervent advocate of progressive measures, an initiator and co-author of modernized programmes for our schools. He has often represented Poland at international conferences on mo-

- 280 - 3 dernizing the teaching of mathematics in primary and secondary schools. In the years 1932-39 he was the Polish delegate to the International Commission for Mathematical Education, in the years 1950-1972 he was chairman of the Polish National Subcommission and in the years 1962-66 - vice-president of the International Commission for Mathematical Education, Presenting Professor Straszewicz's various activities and achievements, we must give due weight to his work in our own Technical University. The mathematicians of our University remember the Professor as an excellent teacher and lecturer, who has aducated three generations of university teachers and has been a model of the perfect teacher and educator. The stu- dents - present-day professors and assistant professors - re- member him as a lecturer excelling in clarity of expression and beautiful languaga. Older members of our teaching staff remember him as the first post-war rector, taking up his du- ties among the ruins of our school. The rector's duties in those days extended far and wide - from rescuing the remnants of our library from utter destruction to setting up a canteen for the staff, whose, members were streaming back to Warsaw in growing numbers, hoping for a quick re-opening of the school. It should also be mentioned that Professor Straszewicz was the initiator of a shortened course of study for engineers, which aimed at providing our recovering industry as quickly as possible with a large number of technically-trained spe- c ialists. The authorities have shown their high appreciation of Professor Straszewicz's work by awarding him seven state de- corations, among them the Order of the Banner of Labour of the 2nd and later of the 1st class, The Medal of National Educations and the highest Teachers' Order of Merit of the Polish People's Republic. Let us turn again to the years immediately following the cessation of military operations in our country. The Hitlerite

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occupation had left behind it not only enormous material da- mage "but also distressing losses among our scholars and scien- tists. About 50% of our research mathematicians had 3ost their lives. In 194-9 the idea was born of setting up an institution whose main aim was to be the spotting out of young people particularly gifted for mathematics and encouraging them to undertake mathematical studies. The Polish Mathematical So- ciety entrusted the task to Professor Straszewicz. "The insti- tution was called the Mathematical Olympiad. Professor Stra- szewicz worked out a set of regulations for it which have stood the test of 24 years and have become a model for seve- ral other specialized olympiads for young people. As Chairman of the Central Committee of the Mathematical Olympiad, Profes- sor 3tra.'J2vi\vicz conducted it for 20 years. About 250OO secon- dary school pupils have passed through the meshes of the Olympiad. A few hundred young talents have been hunted out. Although the time has been short, the fruits of the Olympiad are imposing. Among the former participants of the Olympiad we now count 10 professors, about 40 associate and assistant professors and about 90 doctors doing research in mathematics. It will not be an exaggeration if I say that in the work of rehabilitation of Polish mathematics after the devastations of the last war this is an achievement on a historical scale. Professor Straszewicz s share in it has been outstanding. The Mathematical Olympiad has contributed in an essential way to improving the quality of mathematical instruction in our schools. It has also proved to be a stable concern. When, af·- ter twenty years of chairmanship, Professor Straszewicz re- signed from that post, the job of continuing his work was taken over by the professors and assitant professors who had been former winners of the Olympiad. Professor Straszewicz*s achievement is thus not only great but also lasting. It is particularly worthy of notice that a large part of the results mentioned above have been achieved by Professor Straszewicz in the period after his retirement; This increases

- 282 - 5 still more the respect that Professor Straszewicz enjoys in our University.

The address of the Doctor honoris causa Stefan Strasze- wicz

You Magnificence, Professor Otto, Ladies and Gentlemen. The Warsaw Technical University has conferred upon me a great honour, for which I wish to express my deep gratitude. I am greatly obliged to Professor Otto for having present- ed my activities and my modest achievements in such a favour- able light. The diploma which I have "been granted today is a document of extreme value and importance to me. It is the second doc- tor's diploma in my life. I obtained the first sixty years ago> shortly before the outbreak of the First World War, in the year 19Ή. Within these sixty years, particularly in the second half of this period, the domain of n^ activity - mathematics - has undergone far-reaching transformations.I should like to point out - very briefly - their characteristic features and their significance. The days of njy universitys studies were marked by a grow- ing interest among mathematicians for the newly-developing disciplines of set-theory, topology and mathematical . Not long after these disciplines entered upon a period of rapid progress and their development was soon accompanied by radical changes in the most classical branch of mathematics, namely algebra, giving rise to present-day abstract, or gene- ral, algebra as a theory of algebraic structures. Nowadays mathematicians express their thoughts by means of the conceptual apparatus of and abstract alge- bra. The axiomatic method dominates in the exposition of mathematical results.

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In mathematics the object of investigations is now re- garded as a structure. The structure is composed of a set of objects - the elements of the structure - and certain rela- tions between the elements. The properties of those relations are formulated as a set of . The construction of a the- ory consists in drawing conclusions from the axioms by ap- plying the laws of logic. Por the theory of a structure it is immaterial what actual objects constitute its elements and what actual sense is attached to the relations occurring in it; it is only its formal properties expressed in the axioms that are relevant. Hence follows the great generality and wide applicability of this kind of theory; for the same structures are encountered in different branches of mathematics, and not only in mathematics. It is sufficient to mention the structure of the group, occurring, for example, in physics, in crystal- lography and in other branches of science. Theorems of the general theory of groups - suitably worded - can be used everywhere. The axiomatization of mathematical theory goes together with the formalization of its language, in which a consider- able role is played by the use of set-theoretical and logiçal symbols, ensuring precision and clarity of expression. A new mathematical language may be said to have arisen and spread widely within a comparatively short time. A large num- ber of its symbols have already found their way into other disciplines, e.g. linguistics. The changes which have taken place in mathematics have brought to the fore the problem of teaching mathematics in schools. Since the reform introduced during the early period of the activity of the International Commission for Mathema- tical Education, which was founded in I9O8 and counted among its members a Polish scholar of great merit, Professor Samuel Dickstein, very little has changed in school mathematics. Traditional materials and teaching methods have long been felt to be antiquated. Until a short time ago school mathema- tics dealt with topics which had long ceased to be important,

- 284 - 7 pupils were trained in superfluous calculations and transfor- mations, obsolete notions and terms were in use, while even the most elementary concepts of modern mathematics had no ac- cess to the schools at all. The discrepancy between school teaching of mathematics and the current state of mathematical knowledge was reflacted in what was ¿jocularly alluded to as a system of "double forget- ting": a secondary school graduate embarking on university studies of mathematics had to forget all that he had learned at school, and later, starting his career as a teacher of mathematics, he had to forget in turn all that he had learned at university. It is not to be wondered at that this state of affairs in- duced a strong reformatory movement, which for more than twenty years has been developing both in individual countries and in international organizations. In Poland the task of modernizing the teaching of mathema- tics was undertaken by the Polish Mathematical Society. It launched a widespread campaign, getting up discussions at branch meetings, sending out questionnaires to teachers in secondary schools and universities,and working out well-moti- vated proposals for syllabus changes and improvements. Beginning with the year 1963, new programmes of teaching mathematics in schools have gradually been introduced, modi- fying the subject matter and the approach in accordance with modern demands. Although the reform was moderate and limited in scope, at first its realization encountered considerable difficulties. Upsetting the habits of thought of many tea- chers, it evoked protests, which had repercussions even in the daily and periodical press. In the course of time, however, the initial difficulties were to a large extent overcome, mostly as a result of teacher re-training courses and television lectures organized by the Ministry of Education. At a congress of Polish mathematicians held in Lublin in 1972 it was repeatedly pointed out that owing to the new pro-

- 285 - β grammes the quality of mathematical instruction in schools had improved perceptibly. Today, more than ten years after the reform was inaugur- ated, a need is felt for further improvements. Apart from their obvious merits the new programmes are clearly seen to have certain drawbacks. It is argued that they should be in- fused still more with the unifying concepts of modern mathema- tics and that the formal and logical aspects of teaching should be perfected. This does not mean that we should introduce into the school axiomatized and formalized mathematical theories with all their logical rigour. In my opinion the teaching of young people should be bas- ed on an intuitive approach to every topic dealt with, full use being made of ostensive procedures and particularly of drawings. In this way, the pupils can gradually be led towards precise logical reasoning. History tells us that the new ideas and discoveries of great mathematicians did not arise by way of logical deduction but were the fruit of their creative intuition. Logic, on t3?c other hand, is indispensable for giving the intuitive insights a fixed and precise shape. This is presumably ishat Henry Poin- caré had in mind when he wrote in his famous book "Science and Method": "Sans logique il n'a pas des mathématiques, mais la logique n'est pas tout dans les mathématiques". It is true that intuitive reasoning can sometimes suggest wrong conclusions, but to discern the error and to find ways of rectifying it makes the process of learning more instruc- tive than logical deductions forced upon the pupil a priori. Proceeding from intuition towards logical verification, we have a better chance of arousing the pupils'curiosity and en- couraging them to pose and solve problems on their own. It is my belief that this methodological point of view should be taken into consideration in our further work on problems of teaching mathematics in our country. I hope I shall be -able to continue my contribution to the task which confronts us. - 286 -