Interview with Yohan Hosten
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What field of research does your thesis fall within?
The thesis, entitled "On stochastic properties of the variation in the sum of digits when adding a fixed integer," lies in arithmetic and number theory, but also draws on probability, dynamical systems theory, combinatorics and algorithms. It is supervised by Élise Janvresse and Thierry de la Rue, respectively a professor of mathematics at the université de Picardie Jules-Verne (UPJV) and a CNRS research fellow at the laboratoire de mathématiques Raphaël-Salem, université de Rouen-Normandie.
Why did you choose this topic?
After completing a master's degree in applied mathematics at UPJV, I was looking for a PhD project in probability. Élise Janvresse and Thierry de la Rue approached me with a topic combining arithmetic and probability. I accepted immediately: the subject was relevant and matched what I was looking for. I was drawn to the problem by the simplicity of its statement, and I had already had an excellent experience working with Élise. What more could I ask for? The topic is also surprising to "non-mathematicians": apart from researchers in the field, who would imagine that the behavior of addition is a subject of research?
How does this thesis fit into your plans?
Questions come thick and fast whenever I discuss my topic with "non-mathematicians"—my family or friends, for example. I then have to answer them in the simplest possible terms for an uninitiated audience. Much to my delight, the thesis has therefore allowed me to develop communication and teaching skills that will be extremely useful in my future career as a teacher and researcher (I also hold the agrégation in mathematics). So today I have no regrets about my choice of topic or supervisors! And as a resident of the Somme department, perhaps the subject of sums was made for me after all…
