Prof. Jörg Liesen is a mathematician, expert in the field of numerical algebra, author of several books and numerous research papers. Recipient of the Alston S. Householder Award and a former Heisenberg Professor, he teaches at the TU Berlin and supports PaperHive since the first idea about the platform was born.
Dear Jörg, needless to say how thankful we are for your help from the beginning and for now joining PaperHive’s Advisory Board. What motivated you to help our team even before the platform was live?
The ideas behind PaperHive are great, and the platform has an enormous potential for simplifying research and advancing communication between scientists. I have been fascinated by the project since I first heard about it from Andre. It was a pleasure to work with him as a PhD student, and it was immediately clear to me that I would support him and the entire PaperHive team in their entrepreneurial efforts to bring these ideas to life in a profitable business.
You are teaching mathematics at the TU Berlin, researching, writing academic books. How do you find the balance between research and teaching?
I am passionate about both, so for me the balance comes somehow naturally. In my research I am driven by the challenge and opportunity to obtain a deeper personal understanding of mathematics and its applications. When teaching or giving presentations, I enjoy to convey the beauty of such insights to the audience, and in particular to students. It is all about aha moments!
Research is nowadays unthinkable without international cooperations. Which are you most fruitful partnerships and do borders still matter?
I work and communicate regularly with many international colleagues. This is a privilege and a fun part of my job as a university professor. My most fruitful international collaborations are certainly with colleagues from the Czech Republic and the US, some of them dating back to my student days.
Mathematics is a universal language and knows no borders, and the internet provides immediate access to everything that is published. Nevertheless, there are still unfortunate political and economic borders, and hence limitations to international collaborations. Not every researcher is allowed to travel freely to attend conferences or visit colleagues, and some simply can’t afford it.
You are the coauthor of both the widely used textbook “Linear Algebra”, written in collaboration with Prof. Volker Mehrmann and published by Springer Spektrum, and the monograph “Krylov Subspace Methods”, written in collaboration with Prof. Zdenek Strakos and published by Oxford University Press. What are the main differences between creating a book for students and a book for more advanced researchers? What were the most surprising challenges in the process of research and writing?
I always try to write with the reader in mind, and there is of course a big difference between student readers and experts in some fields. When writing for students I include a lot of motivation, detailed examples, and applications. I provide complete derivations, avoiding statements like “it is easily seen“ as much as possible. Researchers are usually intrinsically motivated, and the pace of the text can be, and actually must be, faster.
Most of my publications, books as well as research papers, result from joint work with colleagues. Cooperating with different personalities always is a challenge, also in research and writing — after all you need to formulate your results in a way that all agree on. Some texts iterate through numerous revisions until this happens, and this requires efficient communication, openness, patience and sometimes persistence. Luckily, so far I was almost always pleasantly surprised by the excellence and determination of my colleagues and collaborators.
I do see similarities to the challenges for PaperHive: It is not only about a great idea, but also about assembling a competent team, building trusting relationships, and working persistently towards a common goal.
History of science and in particular the work of the mathematician Hermann Grassmann (1809-1877) is one of your academic passions. In what ways is history of science relevant for contemporary researchers?
A thorough understanding of historical developments helps us to avoid mistakes that were made in the past. Therefore history is always relevant, not only in science. But since the goal of scientists is to create something new, rather than reinventing the wheel, awareness of historical developments is particularly important for us. In mathematics we establish new results using an existing body of knowledge that has been developed over several thousands of years. It is not enough to know just the facts, like the Pythagorean theorem. The more you know about the underlying ideas and how they evolved, the better. This immediately suggests to learn about the history of science in your area, and to “climb on the shoulder of giants”.
I greatly enjoy reading texts of classical mathematical authors such as Hermann Grassmann. Their writings are often very original and much less formal than today’s standardized and often dry research articles. Since mathematical notation was less developed, they were forced to explain their motivation, ideas, reasoning, and results in words, while modern mathematical texts often mostly consist of formulas. Joseph Rudyard Kipling, author of “The Jungle Book“ and the youngest recipient of the Nobel Price for literature (at age 42 in 1907) wrote in 1928 that only when reading what was written long ago “one realises how absolutely modern the best of the old things are“. I fully agree with that.
You can find some of Prof. Liesen’s articles below:
- Pták‘s nondiscrete induction and its application to matrix iterations /Jörg Liesen/
- The field of values bound on ideal GMRES /Jörg Liesen, Petr Tichý/
- Creating images by adding masses to gravitational point lenses /Olivier Sète, Robert Luce, Jörg Liesen/