How to be a math genius

An escape, a movie, and a math genius

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The Waldviertel is rightly considered romantic. Even as inhospitable - that usually goes hand in hand. It was this inhospitable situation that eighty years ago induced the German Wehrmacht to set up a huge military training area there. Forty villages were - in the official diction of the Third Reich - made "human-clean", that is, evacuated. The fields had not yet been harvested when the tanks were already rehearsing the Blitzkrieg there. That happened in 1938, between the "Anschluss" and the Munich Conference.

The Allentsteig military training area still exists. Many Austrians got to know him, not always to their unadulterated joy. The wolves, who have settled there for several years and enjoy the unspoiled nature, are doing exceptionally well. It couldn't be more romantic.

Border to the dream world

When there in an abandoned cemetery, in the middle of the forest, the sounds of the Marseillaise sound, the border to the dream world seems to have been crossed. The hymn sounds because this year - like every few years - a high-ranking delegation is visiting the place where five thousand French officers lived as prisoners of war from 1940 to 1945, crammed into half a square kilometer. "Little Siberia" they called the spot.

Meanwhile, not only France is interested in the Oflag XVIIA (Oflag stands for "officers camp"). There are also fans in the Austrian armed forces. You support the research of the archaeologist Franz Pieler. What it exposes will soon be overgrown again, but knowledge about the camp is growing. The historian Andreas Kusternig has been working on a book about it for decades. There are three highlights: escape, film and genius.

The escape

It is the main task of every prisoner-of-war officer. As soon as it became clear that the war was not over, the first escape plans were made. There was nothing else to do: according to the Geneva Convention, officers are not allowed to perform labor services.

Now the camp was secured by two barbed wire fences and numerous watch towers. So it was time to dig a tunnel. That was also clear to the German guards who inspected the barracks every day. They became masters in finding cleverly hidden tunnel entrances. Over the years they discovered thirty-one of them. They overlooked the thirty-second. He was not in a barrack, but in an open-air theater right under the eyes of the guards.

The tunnel work lasted five months. After all, there were ninety meters of stony ground to dig. The shaft was so narrow that you could only slip through on your knees. A tube made of empty cans was used for ventilation. The earth, which had been so laboriously dug up, was discreetly distributed around the camp.

Camp inmates counted

The camp inmates were counted at the daily roll call, except on Sundays. Therefore, the escape took place on the night of Saturday, September 18, 1943. It was extended the following night, to a certain extent because of its great success: the camp guard had not noticed anything yet. 132 officers crawled through the narrow hole. During the Second World War there was no major mass exodus from a prisoner-of-war camp.

After the tunnel, of course, you weren't free, but in one of the largest military training areas of the Wehrmacht, i.e. in the lion's den. The settlements were deserted, the church bells mute, the forest full of uniformed men. Soon the first refugees were brought back to the camp; and most of the others over the weeks. In total, only fourteen men escaped.

Disgraced Wehrmacht

The Wehrmacht was embarrassed by the outbreak. She affirmed in the barracks: "Breaking out is no longer a sport." Those who had fled would be shot without a call. When, six months later, 76 British airmen broke out of Oflag III near Sagan, 50 of them perished.

In the Oflag XVIIA there was not only a theater but also a cinema for the prisoners. The program was of course chosen by the German camp management. What they didn't know: The camp inmates not only consumed films, they also produced one. Of course, this had to be done in strict secrecy. Photography and filming were strictly forbidden. Hence the name of the film Sous le manteauUnder the coat: The camera was always hidden, and a sophisticated network of scouts made sure that the guards did not notice anything.

The film is a unique document. Not only everyday scenes in the camp were filmed, but also the adventurous circumstances of the filming itself: for example, how to hide rolls of film in wooden slippers or to warn each other that a patrol is approaching.

The work in the escape tunnel was also filmed. Apparently the cameraman was immune to claustrophobia. And when, after the mass exodus, a grim-looking Wehrmacht commission inspected the camp to find out how such a scandal could happen, the commission was filmed from behind.

The genius

As in other officers' camps, the French prisoners were allowed to do sports, publish a camp newspaper, make music and even found a camp university. At the head of this university was a humble artillery reserve lieutenant named Jean Leray. The man in his mid-thirties already enjoyed a worldwide reputation as an outstanding mathematician. So he was elected rector, which occasionally gave him conflicts with the camp administration. The level of the university was remarkable. The degrees it conferred were later recognized without hesitation. There were lectures on almost everything, from Arabic studies and astronomy to civil law and cell division - and mathematics too.

Leray had previously worked on hydrodynamics and the Navier-Stokes equations, one of the most important and enigmatic objects in applied mathematics. Now he worried that the Germans might force him to work for them - Geneva Convention or not. Hydrodynamics could be useful, for example when designing submarines. That is why Leray turned to algebraic topology during his imprisonment. The area was less familiar to him, but one thing seemed clear: there were no applications in sight.

Leray avoided any contact with German mathematicians; but he was allowed to correspond with Swiss colleagues from time to time, and through this detour, short reports to the Académie des Sciences de Paris appeared under his name as early as 1942. In it he regretted that, under the circumstances, he was unable to guarantee the novelty of his theory.

Do not worry

He didn't have to worry: the results were groundbreaking and original and should inspire the next generation of top mathematicians. As a kind of recognition, Leray was appointed professor at the Sorbonne in 1942 - purely symbolically, of course, because his involuntary address remained a poorly heated barrack in Oflag XVIIA, in which he shared a room with a hundred fellow sufferers. It was not until 1945, after the liberation, that he was able to take up the Paris professorship and soon afterwards he was offered a call to the Collège de France, France's most prestigious chair.

He left the algebraic topology to the younger generation and turned back to his main topic, the partial differential equations. What had been a secondary topic for him, taken up as a kind of camouflage, rapidly developed into one of the most important mathematical subjects of the present day.

Jean Leray lived until 1998. He received pretty much all the prizes and awards one can get for mathematics. But his best time, "his finest hour", was the heroic interlude at the Allentsteig military training area. (Karl Sigmund, May 2nd, 2018)