Charles-Jean de la Vallée Poussin

Son of a mineralogy professor at Leuven, De la Vallée Poussin studied engineering before devoting himself to pure mathematics, appointed professor of calculus and analysis at Leuven in 1893. He tackled the legendary Riemann hypothesis problem regarding the distribution of primes.

In 1896, utilizing complex analysis and properties of the Riemann zeta function, he published his proof that the number of primes less than x asymptotically approaches x/ln(x). He also made foundational contributions to Chebyshev approximation theory and Lebesgue integration.