Cauchy, Augustin Louis, Baron 1789-1857
French mathematician

Born in Paris, he taught mathematics at the �cole Polytechnique, and after the 1830 revolution lived in exile in Turin and Prague, returning to Paris in 1838. He did important work on ordinary and partial differential equations, advocated the wave theory of light following Augustin Fresnel's work, and gave a substantial impetus to the mathematical theory of elasticity. He is remembered as the founder of the theory of functions of a complex variable, which was to play a leading role in the development of mathematics during the rest of the 19th century. In algebra he gave a definitive account of the theory of determinants, and developed the ideas of permutation groups which had appeared in the work of Joseph Luis de Lagrange and �variste Galois.