Described by his biographer, Paul Hoffman, as "probably the most eccentric mathematician in the world," Erdős spent most of his adult life living out of a suitcase.[16] Except for some years in the 1950s, when he was not allowed to enter the United States based on the accusation that he was a Communist sympathizer, his life was a continuous series

Erdős pursued and proposed problems in discrete mathematics, graph theory, number theory, mathematical analysis, approximation theory, set theory, and probability theory.[5] Much of his work centered around discrete mathematics, cracking many previously unsolved problems in the field. He championed and contributed to Ramsey theory, which studies

Paul Erdős (Hungarian: Erdős Pál [ˈɛrdøːʃ ˈpaːl]; 26 March 1913 – 20 September 1996) was a renowned Hungarian mathematician. He was one of the most prolific mathematicians and producers of mathematical conjectures[2] of the 20th century.[3]

His colleague Alfréd Rényi said, "a mathematician is a machine for turning coffee into theorems",[22] and Erdős drank copious quantities (this quotation is often attributed incorrectly to Erdős,[23] but Erdős himself ascribed it to Rényi[24]). After his mother's death in 1971 he started taking antidepressants and amphetamines, despite the concern