Gaston Maurice Julia (3 February 1893 – 19 March 1978) was a French mathematician who devised the formula for the

Julia set In complex dynamics, the Julia set and the Classification of Fatou components, Fatou set are two complement set, complementary sets (Julia "laces" and Fatou "dusts") defined from a function (mathematics), function. Informally, the Fatou set of ...

. His works were popularized by

Benoit Mandelbrot Benoit B. Mandelbrot (20 November 1924 – 14 October 2010) was a Polish-born French-American mathematician and polymath with broad interests in the practical sciences, especially regarding what he labeled as "the art of roughness" of phy ...

; the Julia and Mandelbrot

fractal In mathematics, a fractal is a Shape, geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scale ...

s are closely related. He founded, independently with

Pierre Fatou Pierre Joseph Louis Fatou (28 February 1878 – 9 August 1929) was a French mathematician and astronomer. He is known for major contributions to several branches of mathematical analysis, analysis. The Fatou lemma and the Fatou set are named aft ...

, the modern theory of holomorphic dynamics.

Military service

Julia was born in the

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

n town of Sidi Bel Abbes, at the time governed by the French. During his youth, he had an interest in mathematics and music. His studies were interrupted at the age of 21, when France became involved in

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

and Julia was conscripted to serve with the army. During an attack he suffered a severe injury, losing his nose. His many operations to remedy the situation were all unsuccessful, and for the rest of his life he resigned himself to wearing a leather strap around the area where his nose had been.

Career in mathematics

Julia gained attention for his mathematical work at the age of 25, in 1918, when his 199-page ''Mémoire sur l'itération des fonctions rationnelles'' ("Memoir on the Iteration of Rational Functions") was featured in the ''

Journal de Mathématiques Pures et Appliquées The ''Journal de Mathématiques Pures et Appliquées'' () is a French monthly scientific journal of mathematics, founded in 1836 by Joseph Liouville (editor: 1836–1874). The journal was originally published by Charles Louis Étienne Bachelier. ...

''. This article gained immense popularity among mathematicians and earned him the ''Grand Prix des Sciences Mathématiques'' of the

French Academy of Sciences The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...

in 1918. But after this brief moment of fame, his works were mostly forgotten until

mentioned them in his works on

s in the French book ''Les Objets Fractals: Forme, Hasard et Dimension'', later translated in 1977 as ''Fractals: Form, Chance and Dimension''. On 19 March 1978, Julia died in Paris at the age of 85. Julia was also father to Marc Julia, the French organic chemist who invented the Julia olefination.

World War Two and collaboration

Julia collaborated with

Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...

during the

occupation of France The Military Administration in France (; ) was an Military Administration (Nazi Germany), interim occupation authority established by Nazi Germany during World War II to administer the occupied zone in areas of northern and western French Third ...

; recruiting French mathematicians to collaborate with the Zentralblatt für Mathematik. He was suspended for a few weeks after the

liberation of France The liberation of France () in the Second World War was accomplished through diplomacy, politics and the combined military efforts of the Allied Powers, Free French forces in London and Africa, as well as the French Resistance. Nazi Germany in ...

, but according to Michèle Audin:

Books

*''Oeuvres'', 6 vols., Paris, Gauthier-Villars 1968-1970 (eds.

Jacques Dixmier Jacques Dixmier (born 24 May 1924) is a French mathematician. He worked on operator algebras, especially C*-algebras, and wrote several of the standard reference books on them, and introduced the Dixmier trace and the Dixmier mapping. Biogra ...

, Michel Hervé, with foreword by Julia) *''Leçons sur les Fonctions Uniformes à Point Singulier Essentiel Isolé'', Gauthier-Villars 1924 (rédigées par P. Flamant) *''Eléments de géométrie infinitésimale'', Gauthier-Villars 1927 *''Cours de Cinématique'', Gauthier-Villars 1928, 2nd edition 1936 *''Exercices d'Analyse'', 4 vols., Gauthier-Villars, 1928–1938, 2nd edition 1944, 1950 *''Principes Géométriques d'Analyse'', 2 vols., Gauthier-Villars, 1930, 1932 *''Essai sur le Développement de la Théorie des Fonctions de Variables Complexes'', Gauthier-Villars 1933 *''Introduction Mathématique aux Theories Quantiques'', 2 vols., Gauthier-Villars 1936, 1938, 2nd edition 1949, 1955 *''Eléments d'algèbre'', Gauthier-Villars 1959 *''Cours de Géométrie'', Gauthier-Villars 1941 *''Cours de géométrie infinitésimale'', Gauthier-Villars, 2nd edition 1953 *''Exercices de géométrie'', 2 vols., Gauthier-Villars 1944, 1952 *''Leçons sur la représentation conforme des aires simplement connexes'', Gauthier-Villars 1931, 2nd edition 1950 *''Leçons sur la représentation conforme des aires multiplement connexes'', Gauthier-Villars 1934 *''Traité de Théorie de Fonctions'', Gauthier-Villars 1953 *''Leçons sur les fonctions monogènes uniformes d'une variable complexe'', Gauthier-Villars 1917 *''Étude sur les formes binaires non quadratiques à indéterminées réelles ou complexes, ou à indéterminées conjuguées'', Gauthier-Villars 1917

References

External links

* * * ''Memoir on iteration of rational functions'', English translation in parts
1/72/73/74/75/76/77/7

Downloadable articles at Numdam

Diplomica GmbH Hamburg (2008) * Daniel Alexander, Felice Iavernaro, Alessandro Rosa
''Early days in complex dynamics: a history of complex dynamics in one variable during 1906-1942''
History of Mathematics 38, American Mathematical Society 2012 {{DEFAULTSORT:Julia, Gaston 1893 births 1978 deaths École Normale Supérieure alumni 20th-century French mathematicians University of Paris alumni Academic staff of the University of Paris Members of the French Academy of Sciences People from Sidi Bel Abbès People without noses French military personnel of World War I Pieds-noirs Emigrants from French Algeria to France