# Who killed professor X?

The author has won several prizes for his education project *Who killed professor X?*. Now we have this graphical novel with beautiful graphics by Thanasis Gkiokas also available in English (the Greek original is from 2010).

It is a detective story in which several of the greatest historic mathematicians become all suspects for a murder on a colleague. A French inspector Gérard, assisted by a mathematician Kurt, has to find the murderer of a mathematician X. The problem is to find out which suspect was at a short distance from the place of the delict. The readers can find out for themselves by going through the files and computing the distances on a map of the hotel. A short sketch characterizing the achievements of each suspect and some reason why they could have wanted to murder X is explained by Kurt to the inspector as their possible guilt is investigated. The file of each suspect is concluded by a statement made under oath about where they were at the time of the murder and some geometric information about the hotel. All the suspects are indicated by their first name but at the end, after the mystery has been solved, some more historical information is provided about René (Descartes), Constantin (Carathéodory), Pierre (Fermat), Isaac (Newton), Blaise (Pascal), Leonhard (Euler), Carl Friedrich (Gauss), Bernhard (Riemann), (Marie-)Sophie (Germain), Évariste (Galois), and Kurt (Gödel). There is one unfortunate play of words that is lost in translation. The X in Greek is pronounced as Chi, while it refers to (David) Hilbert.

Meanwhile we learn about Hilbert's *Wir müssen wissen — wir werden wissen! (``We must know — we will know!'')*, about the Leibniz-Newton controversy, the Köninggsberg bridges problem, the golden ratio (explained by Pheidias — a Greek sculptor of 5th century BC), that Marie-Sophie Germain was inspired by Archimedes and wanted to become a mathematician but she had to pretend to be a man (*Monsieur Le Blanc*) because she was not accepted as a female among mathematicians, that Voltaire described Émily du Châtelet as *``She was a great man whose only fault was to be born a woman''*, that the revolutionary Galois had problems in getting his results accepted by Cauchy and Poisson, and many other anecdotes and stories.

The conscientious and studious reader who has been solving the distance problems while reading along will find solutions to check his or her computations at the end of the book. Only mathematics of secondary school is needed. However, the finale is a marvelous *coup de théâtre*. The surprising outcome is not illogical though since it corresponds to the historical development that was triggered by Hilbert who formulated his great unsolved mathemaical problems at the International Congress of Mathematicians in Paris in 1900.

This is a wonderful booklet of fiction, but based on historical incidents. In the foreword, Andriopoulos states that the book *... is aimed at two kinds of readers: those who have some knowledge of mathematics, and those who have no knowledge of mathematics*. Because "some knowledge" is a flexible concept ranging from zero to infinity, it is safe to say that anybody will love the book. It is a fantastic present that you can give to anybody between 9 and 99.

**Submitted by Adhemar Bultheel |

**23 / Jun / 2015