Paul Pierre Lévy (September 15, 1886 - December 15, 1971) was a French mathematician who was active especially in probability theory, introduced martingales and Lévy flights. Lévy processes, Lévy measures, Lévy's constant, the Lévy distribution and the fractal Lévy C curve. September 15 is the 258th day of the year (259th in leap years). ... 1886 is a common year starting on Friday (click on link to calendar) Events January 18 _ Modern field hockey is born with the formation of The Hockey Association in England. ... December 15 is the 349th day of the year (350th in leap years) in the Gregorian calendar. ... 1971 is a common year starting on Friday (click for link to calendar). ... Probability theory is the mathematical study of probability. ... A separate article treats the device for fastening horses bridles or dogs collars called a martingale. ... A fractal is a geometric object which can be divided into parts, each of which is similar to the original object. ...

Lévy was born in Paris, the son of Lucien Lévy, an Examiner at the École Polytechnique . Lévy also attended the École Polytechnique and published his first paper in 1905 at the age of 19, while still an undergraduate. After graduation he spent a year in military service and then studied for three years at the École des Mines, where he became a professor in 1913. The cadets of Polytechnique rushed to the defense of Paris against the foreign armies in 1814. ... 1905 was a common year starting on Sunday (see link for calendar). ... 1913 is a common year starting on Wednesday. ...

During World War I Lévy did mathematical analysis work for the French artillery. In 1920 he was appointed Professor of Analysis at the École Polytechnique, where his students included Benoît Mandelbrot. He remained at the École Polytechnique until his retirement in 1959. Ypres, 1917, in the vicinity of the Battle of Passchendaele. ... 1920 is a leap year starting on Thursday (link will take you to calendar) Events January January 7 - Forces of Russian White admiral Kolchak surrender in Krasnoyarsk. ... Benoît Mandelbrot was the first to use a computer to plot the Mandelbrot set. ... 1959 was a common year starting on Thursday (link will take you to calendar). ...