Royal Decoration for Henk Broer

On Friday 20 November, Mayor P.E.J. den Oudsten of the municipality of Groningen has presented Prof. H.W. Broer with a Royal Decoration on the occasion of his retirement. Broer is a professor and international top researcher in the field of dynamical systems in mathematics. He has been made a Knight of the Order of the Netherlands Lion.

The field in which Henk Broer (Diever, 1950) conducts research focuses on the development of the mathematical language for defining changes in states and motions of physical and mathematical phenomena in terms of time. The particular focus of Broer’s work is on describing sudden, chaotic transitions in complex systems.

Dynamic systems

Broer has had a huge impact on mathematics, both nationally and internationally. He has published more than 125 scientific articles in leading journals and his work is frequently cited. Broer is also a very broad-based mathematician, who has worked successfully with experts from various other associated fields. Almost every specialist in the field of dynamical systems is familiar with Broer’s work, and he has had a significant influence on the work of many others.

Broer’s particular contribution to his field concerns the development of the parametric KAM theory devised by the famous mathematicians Kolmogorov, Arnold and Moser, which studies perturbations in periodic motions. These motions are common in all kinds of fundamental and applied science, such as mathematical physics, economic markets, biophysics, celestial mechanics and climate theory. By making good use of the available variables in a dynamical system, Broer showed that many periodic motions are persistent; in other words, they do not stop if the system is disturbed by an external force. Broer has spent the last few decades developing these mathematical techniques into an extensive mathematical programme.

Interdisciplinary character

In addition, Broer has trained countless young mathematicians. His considerable versatility as a mathematician is reflected in the interdisciplinary character of the PhD research he has supervised. As things currently stand, a staggering 26 PhD candidates have been successful under his supervision, an achievement that few mathematicians can match. An active mathematician would normally expect to supervise a maximum of 10 PhD candidates during his/her career.

The scientific journal Indagationes Mathematicae, published under the auspices of the Royal Netherlands Academy of Arts and Sciences (KNAW), was in dire straits at the turn of the 21^st century. After taking over as editor-in-chief, Broer turned the tide and the publication regained its former status as a leading scientific journal of international allure. All his peers, including the critical international vanguard, were amazed. In 2008, Broer’s international and national fame earned him membership of the Royal Netherlands Academy of Arts and Sciences (KNAW).

As chair of the Royal Dutch Mathematical Society (KWG), Broer played a key role in improving the position of mathematics in the Netherlands by setting up the Dutch Mathematics Platform, a joint platform of the KWG and the Dutch Association of Mathematics Teachers (NVvM).

Popularization of mathematics

Throughout his career, Broer has always striven to raise the profile of mathematics among a wider public. As a member of the Future of Mathematics in Education Committee, for example, he helped to advance expertise among maths teachers, and was a co-organizer and a frequent speaker at the National Mathematics Days.

Broer recognized that providing good, affordable books about mathematics was key to making the field more appealing to a wider audience. He therefore spent many years working on the editorial board of Epsilon publications for mathematics, editing various series for academia, for the highest years of pre-university education and for honing people’s basic knowledge of mathematics.

Broer’s exceptional services to popularizing mathematics and natural sciences are particularly evident in the numerous lectures he has given to the general public and in schools. It is also worth mentioning his chairmanship of the Bernoulli Foundation for Mathematics in Groningen, which organizes the annual (free) Bernoulli Lecture where prominent international guest speakers present topical subjects from the field of mathematics and natural sciences to a wide public.

From the very start of his career in Groningen, Broer has been involved in organizing ‘Teachers’ Day’ in the Department of Mathematics at the University of Groningen. This annual workshop for maths teachers and educationalists attracts around 100 visitors, who come to attend lectures and workshops about the content, teaching methods and policies for maths teaching in the Netherlands.

Finally, Broer is also an active advocate of lifelong learning. He coordinates various mathematics courses for higher education for the elderly (HOVO) taught at the Senior Academy (University of the Third Age) in Groningen, such as a course in 2015 entitled New Developments in Mathematics.