**Samuel Eilenberg** was a Polish-born American mathematician who worked on algebraic topology and homological algebra. He was one of the founders of category theory.

- Sammy, as Eilenberg was always called, studied at the University of Warsaw.
- It is not surprising that Eilenberg's interests quickly turned towards point set topology which, of course, was an area which flourished at the University of Warsaw at that time.
- A remarkable collection of mathematicians were on the staff at the University of Warsaw while Eilenberg studied there.
- Eilenberg was awarded his MA from the University of Warsaw in 1934.
- It was there that Eilenberg met Banach, who led the Lwów mathematicians.
- Most of Eilenberg's publications from this period were on point-set topology but there were signs, even at this early stage of his career, that he was moving towards more algebraic topics.
- It was one of a truly remarkable collection of papers published by Eilenberg for, from his days as an undergraduate up until 1939 when he left Poland for the United States, he published 37 papers.
- This was an excellent place for Eilenberg to begin his teaching career in the United States for there he could interact with leading topologists.
- Eilenberg lectured at the conference on Extension and classification of continuous mappings.
- Eilenberg was only an instructor for one year, then in 1941 he was promoted at assistant professor at the University of Michigan.
- In 1948, the year after he took up the post at Columbia, Eilenberg became a US citizen.
- Perhaps the most obvious feature of Eilenberg's work was the amount which was done in collaboration with other mathematicians.
- In 1949 André Weil was working at the University of Chicago and he contacted Eilenberg to ask him to collaborate on writing about homotopy groups and fibre spaces as part of the Bourbaki project.
- Eilenberg became a member of the Bourbaki team spending 1950-51 as a visiting professor in Paris and participating in the two week summer meetings until 1966.
- One of the first collaborations which Eilenberg entered was with Mac Lane.
- The two first met in 1940 in Ann Arbor and from that time until about 1954 the pair produced fifteen papers on a whole range of topics including category theory, cohomology of groups, the relation between homology and homotopy, Eilenberg-Mac Lane spaces, and generic cycles.
- Ann Arbor again provided the means to bring Eilenberg and Steenrod together.
- Eilenberg had written a definitive treatment of singular homology and cohomology in a paper in the Annals of Mathematics in 1944.
- In 1948 Eilenberg, in a joint paper with Chevalley, gave an algebraic approach to the cohomology of Lie groups, using the Lie algebra as a basic object.
- Another collaboration of major importance was between Eilenberg and Henri Cartan.
- However as we mentioned above Eilenberg spent 1950-51 in Paris and it was during this time that they made remarkable progress.
- We should mention another major two volume text which Eilenberg published in 1974 and 1976.
- It was a topic which Eilenberg had been interested in from 1966 onwards and it is worth noting that it is one of the few major works by Eilenberg which he worked on alone.
- There was another side to Eilenberg however, for he was a dealer in the art world in which he was known as "Professor".
- In a gesture characteristically marked by its generosity and elegance, Sammy in 1987 donated much of his collection to the Metropolitan Museum of art in New York, which in turn was thus motivated to contribute substantially to the endowment of the Eilenberg Visiting Professorship in Mathematics at Columbia university.
- Eilenberg received many honours for his work.
- Finally let us give a quote regarding Eilenberg's personality.

Born 30 September 1913, Warsaw, Russian Empire (now Poland). Died 30 January 1998, New York, USA.

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Bourbaki, Origin Poland, Topology, Prize Wolf

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive