Henri Lebesgue
died 76 years ago
26th July 1941

Henri Lebesgue formulated the theory of measure in 1901 and the following year he gave the definition of the Lebesgue integral that generalises the notion of the Riemann integral.

Find out more at:
http://www-history.mcs.st-andrews.ac.uk/Mathematicians/Lebesgue.html