Universidad de Rochester

Biography

His/her father was employed in a printing works, and died when it was very young. Then, his/her mother worked very hard so that it can make studies. Raise shining as of the elementary school, Lebesgue studied later with the National university.

He taught with the college of Nancy and that of Rennes. He will then be made know by his theory of the measurement, which prolongs the first important work of Emile Borel, one of its professors and later his friend.

He developed a theory measurable functions (1901) while basing himself on the results of Emile Borel: the tribes boréliennes.

Henri Leon Lebesgue revolutionized and generalized the integral calculus. Its theory of integration (1902-1904) is extremely convenient of employment, and meets the needs for the physicists. Indeed, it makes it possible to seek and prove the existence of Primitive S for “irregular” functions and recovers various former theories which are particular cases:

functions in staircase and continuous functions of Riemann
limited functions of Darboux
functions with limited variation of Stieltjes.

It is named professor with the Sorbonne in 1910, then with the Collège de France in 1921. It also gives courses to the University of industrial physics and chemistry of 1927 with 1937 and with the National university of Sevres. He will be elected with the Academy of Science in 1922.

Like his father, Henri Leon Lebesgue had a defective health throughout his life. He Maria with the sister of one of his comrades of the National university, and had two children, Suzanne and Jacques.

Anecdotes and testimonys

“ I attended the first course of Lebesgue… It should be said that by tradition it was very solemn, the professor tells a little his past, it speaks about the people who preceded it in her pulpit or who were her Masters (...) I must say that there was not a course of Lebesgue where one did not laugh in an infinitely pleasant way. I even suspect as at least one the third of people came during Lebesgue to have fun; there was nothing vulgar, nor usually in jokes when it made exits. But it was infinitely interesting, infinitely deep. Lebesgue was a little like Bernstein from this point of view, it forever known to make a licked demonstration, but it very inspiring because was very inspired. Lebesgue was about of the same age that Bernstein and I believe that it took as a starting point the same idea, that to make a course, it is necessary to reflect while it is made it, and not to remember. (...) The courses of Call, it was too beautiful, I do not dare to say to be honest , but finally it was too beautiful to be mechanics. With Lebesgue, on the contrary it was each time: Ah, I said a silly thing, let start again to me. It started again and everyone reflected at the same time.” (Szolem Mandelbrojt)
“At the beginning of 1941, Henri Lebesgue gave to the Collège de France its last annual teaching. Already, the evil which was to carry it later a few months had come to be added to the sufferings morals of the defeat and the enemy Occupation. It could hardly move with foot and the city was deprived of means of transport on the surface. It had to call upon these apparatuses holding of the sedan-chair and the Bicyclette which were useful then for the patients and could thus make its course. In its eyes that meant to make its duty, disciplines more necessary than ever for those who, like, had to him faith in the release and the raising of the Fatherland. ” (Paul Montel)

Works

Lessons on the integration and the research of the primitive functions (2nd ED. 1928), ED. Gauthier-Villars, Paris
Lessons on the trigonometrical series (1906), ED. Gauthier-Villars, Paris
To the measure of the sizes (1915), ED. A. Kundig, Geneva
conical the (1942, posth.), ED. Gauthier-Villars, Paris
Lessons on geometrical constructions (1950, posth. starting from the notes of Miss J. Felix), ED. Gauthier-Villars, Paris
shortly after the integral. Letters with Emile Borel , (2004), ED Vuibert, Paris.

See too

Intégrale of Lebesgue
the nuance enters integration within the meaning of Riemann and Lebesgue

External bonds

Some articles of Lebesgue in the numerical file NUMDAM.