**Jacques Feldbau** was a French mathematician who worked on differential geometry and topology.

- Armand Feldbau was a wholesale distributor of butter, eggs and cheese having a business in the Rue Hannong, Strasbourg.
- Jacques and Janette were very close as they were growing up.
- This Strasbourg address would remain Feldbau's home address for the rest of his life.
- On 1 October 1920 Feldbau began his primary school education in the Gymnasium Fustel de Coulanges.
- Feldbau remained at this school until 10 July 1925.
- Feldbau was eleven years old in 1925 and he spent the school year 1925-26 at the rabbinical school in Paris.
- Feldbau was awarded his Premier Baccalauréat on completing Class 1e and in the following year La Tribune juive notes on 22 July 1932 that Jacques Feldbau passed the baccalaureates in mathematics and philosophy.
- Feldbau took the first of these on 30 May 1938 and, being one of the 51 best students, he continued to take two further written papers on descriptive geometry and calculating, and two oral examinations, one on elementary mathematics and the other on special mathematics.
- Of the 51 students who were allowed forward to take these examinations, Feldbau was ranked eighth.
- La Tribune Juive notes on 12 August 1938 that it has pleasure in announcing that Jacques Feldbau of Strasbourg has successfully passed the Agrégation in mathematics.
- Feldbau had been particularly inspired to undertake research in topology because of the course he attended given by André Weil.
- He asked Weil about possible topics for his dissertation and Weil suggested that Feldbau speak to Charles Ehresmann who had just been appointed as a lecturer at Strasbourg.
- As Feldbau began his postgraduate studies, life in Strasbourg was not easy for Jews.
- By the time that Feldbau began research in the autumn of 1938 the situation had become nasty.
- Feldbau tore the sign down and a scuffle with some guests at the Maison resulted.
- Feldbau and some fellow students were then approached by the police and arrested.
- Around this time the same group of students were involved in an incident with a pro-Nazi bookshop, but it is uncertain whether Feldbau was one of the students who damaged the store.
- However, on the mathematical side Feldbau's work was progressing well and he wrote the paper Sur la classification des espaces fibrés Ⓣ(On the classification of fiber spaces) which was published by the Academy of Sciences in 1939.
- Not only was Feldbau's mathematics progressing well, but so were his sporting activities.
- Feldbau had already completed military training as an officer cadet earlier in 1939, this having been postponed earlier when he was a guest student at the ENS.
- With the outbreak of war, France mobilised and Feldbau was posted to the airbase at Tours where he had already undertaken training.
- Feldbau was demobilized and became a high school teacher in Châteauroux, a small town in central France, taking up this position in the autumn of 1940.
- Châteauroux, where Feldbau became a teacher, was in Vichy France.
- Although he was in Châteauroux, Feldbau must have kept in contact with his Strasbourg colleagues since he clearly knew exactly what was happening.
- Clermont-Ferrand is where the University of Strasbourg moved in September 1939 before the German armies invaded France so by the time Feldbau is writing this the University of Strasbourg had been located there for over a year.
- In December 1940, dismissed from his teaching position in Châteauroux, Feldbau arrived in Clermont-Ferrand.
- Feldbau had been an auditor at the ENS - he had not succeeded in entering the ENS because, as a practising Jew, he had refused to pass one of the exams on a Saturday.
- During the sessions 1941-42 and 1942-43 Feldbau was enrolled as a doctoral student in mathematics.
- To earn money to live Feldbau gave private mathematics lessons but he also learned Russian, played the piano, learned the profession of a metal lathe operator, and made new friends with whom he often went for long bicycle rides in the mountains.
- In collaboration with his thesis advisor Ehresmann, Feldbau published the joint paper Sur les propriétés d'homotopie des espaces fibrés Ⓣ(On the homotopy properties of fibre spaces) in 1941.
- After this, in order to protect his Jewish identity, Feldbau published his mathematics under the pseudonym Jacques Laboureur.
- Feldbau decided to go underground and left the student accommodation where he was living.
- German soldiers and Gestapo agents had raided the building during the night and were interrogating the students when Feldbau arrived.
- Taken to the La Malcoiffée prison in Moulins, Feldbau gave lessons in astronomy, mathematical games and topology to fellow prisoners.
- Feldbau was put to work as the secretary in the surgical block of the infirmary.
- To take their minds off the terrible situation they were in, a number of mathematicians in the camp, led by Feldbau, set and solved mathematical problems each day.
- Feldbau is said to have discussed Fermat's Last Theorem with a fellow mathematician as they marched.
- By this time Feldbau was very weak and he died of exhaustion in the concentration camp on 22 April 1945, two days before the liberation of the camp and fifteen days before the war ended.

Born 22 October 1914, Strasbourg, Alsace, Germany (now France). Died 22 April 1945, Ganacker, Bavaria, Germany.

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Astronomy, Topology

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive