Mathematicians Of The Day

29th April

On this day in 1901, Lebesgue published his famous paper Sur une généralisation de l'intégrale définie in the Comptes Rendus of the French Academy of Sciences. In this he gave the definition of the Lebesgue integral that generalises the notion of the Riemann integral by extending the concept of the area below a curve to include many discontinuous functions.

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Quotation of the day

From Henri Poincaré
When one tries to depict the figure formed by these two curves and their infinity of intersections, each of which corresponds to a doubly asymptotic solution, these intersections form a kind of net, web or infinitely tight mesh . . . . One is struck by the complexity of this figure that I am not even attempting to draw.