**Augustin-Louis Cauchy** pioneered the study of analysis, both real and complex, and the theory of permutation groups. He also researched in convergence and divergence of infinite series, differential equations, determinants, probability and mathematical physics.

- In 1802 Augustin-Louis entered the École Centrale du Panthéon where he spent two years studying classical languages.
- From 1804 Cauchy attended classes in mathematics and he took the entrance examination for the École Polytechnique in 1805.
- In 1810 Cauchy took up his first job in Cherbourg to work on port facilities for Napoleon's English invasion fleet.
- Cauchy was a devout Catholic and his attitude to his religion was already causing problems for him.
- In addition to his heavy workload Cauchy undertook mathematical researches and he proved in 1811 that the angles of a convex polyhedron are determined by its faces.
- Cauchy felt that he had to return to Paris if he was to make an impression with mathematical research.
- Back in Paris Cauchy investigated symmetric functions and submitted a memoir on this topic in November 1812.
- An academic career was what Cauchy wanted and he applied for a post in the Bureau des Longitudes.
- In this last election Cauchy did not receive a single one of the 53 votes cast.
- In 1815 Cauchy lost out to Binet for a mechanics chair at the École Polytechnique, but then was appointed assistant professor of analysis there.
- In 1817 when Biot left Paris for an expedition to the Shetland Islands in Scotland Cauchy filled his post at the Collège de France.
- Cauchy was the first to make a rigorous study of the conditions for convergence of infinite series in addition to his rigorous definition of an integral.
- Cauchy did not have particularly good relations with other scientists.
- Political events in France meant that Cauchy was now required to swear an oath of allegiance to the new regime and when he failed to return to Paris to do so he lost all his positions there.
- In 1831 Cauchy went to Turin and after some time there he accepted an offer from the King of Piedmont of a chair of theoretical physics.
- In 1833 Cauchy went from Turin to Prague in order to follow Charles X and to tutor his grandson.
- When questioned by Cauchy on a problem in descriptive geometry, the prince was confused and hesitant.
- Cauchy became annoyed and screamed and yelled.
- While in Prague Cauchy had one meeting with Bolzano, at Bolzano's request, in 1834.
- Cauchy returned to Paris in 1838 and regained his position at the Academy but not his teaching positions because he had refused to take an oath of allegiance.
- Cauchy was strongly supported by Biot and Arago but Poisson strongly opposed him.
- Cauchy was elected but, after refusing to swear the oath, was not appointed and could not attend meetings or receive a salary.
- In 1843 Lacroix died and Cauchy became a candidate for his mathematics chair at the Collège de France.
- During this period Cauchy's mathematical output was less than in the period before his self-imposed exile.
- When Louis Philippe was overthrown in 1848 Cauchy regained his university positions.
- Liouville and Cauchy were candidates for the chair again in 1850 as they had been in 1843.
- Subsequent attempts to reverse this decision led to very bad relations between Liouville and Cauchy.
- Another, rather silly, dispute this time with Duhamel clouded the last few years of Cauchy's life.
- Duhamel argued with Cauchy's claim to have been the first to give the results in 1832.
- Poncelet referred to his own work of 1826 on the subject and Cauchy was shown to be wrong.
- However Cauchy was never one to admit he was wrong.
- Numerous terms in mathematics bear Cauchy's name:- the Cauchy integral theorem, in the theory of complex functions, the Cauchy-Kovalevskaya existence theorem for the solution of partial differential equations, the Cauchy-Riemann equations and Cauchy sequences.
- In spite of its vastness and rich multifaceted character, Cauchy's scientific works possess a definite unifying theme, a secret wholeness.
- Cauchy's creative genius found broad expression not only in his work on the foundations of real and complex analysis, areas to which his name is inextricably linked, but also in many other fields.
- His collected works, "Oeuvres complètes d'Augustin Cauchy" Ⓣ(The complete works of Augustin Cauchy) (1882-1970), were published in 27 volumes.

Born 21 August 1789, Paris, France. Died 23 May 1857, Sceaux (near Paris), France.

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Algebra, Analysis, Astronomy, Bourbaki, Group Theory, Number Theory, Physics

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