Wolfgang Doeblin

Wolfgang Doeblin, known in France as Vincent Doblin (17 March 1915 – 21 June 1940), was a French-German mathematician.

Life
A native of Berlin, Wolfgang was the son of the Jewish-German novelist and physician, Alfred Döblin, and Erna Reiss. His family escaped from Nazi Germany to France where he became a citizen. Studying probability theory at the Institute Henri Poincaré under Fréchet, he quickly made a name for himself as a gifted theorist. He became a doctor at age 23. Drafted in November 1938, after refusing to be exempted from military service, he had to stay in the active Army when World War II broke out in 1939, and was quartered at Givet, in the Ardennes, as a telephone operator. There, he wrote down his latest work on the Chapman–Kolmogorov equation, and sent this as a "pli cacheté" (sealed envelope) to the French Academy of Sciences. His company, sent to the sector of the Saare on the ligne Maginot in April 1940, was caught in the German attack in the Ardennes in May, withdrew to the Vosges, and capitulated on 22 June 1940. On 21 June, Doeblin shot himself in Housseras (a small village near Epinal), when German troops came within sight. In his last moments, he burned his mathematical notes.

The sealed envelope was opened in 2000, revealing that Doeblin was ahead of his time in the development of the theory of Markov processes. In recognition of his results, Itô's lemma is now occasionally referred to as the Itô–Doeblin theorem.

His life was the subject of a 2007 movie by Agnes Handwerk and Harrie Willems, A Mathematician Rediscovered.

When he became a French citizen in 1938, he chose the official name of Vincent Doblin. However, he later chose to spell it as Wolfgang Doeblin and it is under this name that all his mathematical papers and professional letters were signed.