新板 窮理図解

What do you do when you are not doing research?
      I’ve always enjoyed spending time with my wife. After the birth of my daughter two years ago, my family life is even more fulfilling. However, I don’t feel that time with my family is separate from the time I spend doing mathematics. I feel I’m thinking in the same way – when engaging in research, dealing with my students, or enjoying playing with my daughter. Dealing equally with mathematics and my dearest daughter may sound as though I am a bit too cold as a father, but I feel that I have the same great affection for mathematics as I do for my daughter.
      Thinking about the essentials of how to associate with or how to establish proper relationships with people has become so much fun that having such an abstract perspective or a mindset based on mathematical speculation is now almost a hobby for me.
      On the other hand, we have to remain cautious about careless generalizations disregarding reality and actual phenomena. For example, one could cause a disaster by dogmatically applying a general educational principal in a certain teaching situation without fully understanding the principals involved or the subtlety of the situation. The reason I believe many people are weary of arguments coming from abstract theory is the prevalence of such careless generalizations. When we use an abstract theory in mathematics, we check very strictly that the specific situation satisfies the conditions making the abstract theory applicable. I think it is very important to form the habit of checking rigorously in each specific situation to see if abstract argument is indeed applicable.

What do you think are good points of Keio University?
      First of all, the students are very highly motivated. While I was staying in France in 2007, I had the opportunity to participate in a number theory workshop known as the UK-Japan Winter School jointly sponsored by Cambridge and Keio universities. I was very impressed with the enthusiasm of Keio students.
      At many Japanese universities, the department of mathematics belongs to the faculty of science. Furthermore, at the University of Tokyo where I studied and Nagoya University where I previously worked, Mathematics belonged to an independent graduate school, which made me feel somewhat isolated from other departments. At Keio University, the Department of Mathematics belongs to the Faculty of Science and Technology, allowing us to be in close contact with the technological departments. I have many opportunities to discuss with faculty from other departments – an advantage creating a health synergy between science and technology. Such a campus environment is probably one reason we have many creative and lively students.

Some words from students
Student A : Prof. Bannai is free of the stereotypical image of a mathematician. He is always willing to advise us even on simple questions and is open-minded enough to take interest in what we say or ask. This broad-mindedness makes his character very attractive. During lectures, he is very enthusiastic and inspires us to study mathematics. When we become stuck with a problem, he kindly gives us hints, often in a subtle manner, to help us along.
Student B : Prof. Bannai is fond of new things and is active enough to get out of campus to check it out himself. Recently he told us about visiting a manufacturer’s showroom in trying an electronic whiteboard; after returning to the lab he enthusiastically explained his impression of the whiteboard. He talks about his interest openly, and laughs when he finds something truly interesting. He is very friendly and reliable mentor.

(Reporter & and text writer: Kaoru Watanabe)