Alfred Errera
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Alfred Errera (1886 – 1960) was a Belgian
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
. Errera studied at the
Université libre de Bruxelles The (French language, French, ; lit. Free University of Brussels; abbreviated ULB) is a French-speaking research university in Brussels, Belgium. It has three campuses: the ''Solbosch'' campus (in the City of Brussels and Ixelles), the ''Plain ...
, where he received his Ph.D. in 1921 with dissertation ''Du coloriage des cartes et de quelques questions d'analysis situs''. In his dissertation he introduced what is now called the Errera graph, which is a counterexample to the validity of the alleged proof of the four color theorem by
Alfred Kempe Sir Alfred Bray Kempe FRS (6 July 1849 – 21 April 1922) was a mathematician best known for his work on linkages and the four colour theorem. Biography Kempe was the son of the Rector of St James's Church, Piccadilly, the Rev. John Edwar ...
. From 1928 to 1956 he was a professor at the Université libre de Bruxelles. He did research on
topology Topology (from the Greek language, Greek words , and ) is the branch of mathematics concerned with the properties of a Mathematical object, geometric object that are preserved under Continuous function, continuous Deformation theory, deformat ...
, especially the theory of
polyhedra In geometry, a polyhedron (: polyhedra or polyhedrons; ) is a three-dimensional figure with flat polygonal faces, straight edges and sharp corners or vertices. The term "polyhedron" may refer either to a solid figure or to its boundary su ...
and the
Jordan curve theorem In topology, the Jordan curve theorem (JCT), formulated by Camille Jordan in 1887, asserts that every ''Jordan curve'' (a plane simple closed curve) divides the plane into an "interior" region Boundary (topology), bounded by the curve (not to be ...
. With Théophile Lepage he conducted a seminar on analysis at the University of Brussels. During World War I, he worked on the
acoustic source localization Acoustic location is a method of determining the position of an object or sound source by using sound waves. Location can take place in gases (such as the atmosphere), liquids (such as water), and in solids (such as in the earth). Location can ...
of artillery fire and from 1921 to 1938 taught courses on this subject at the Royal Military Academy. Errera was an Invited Speaker at the
International Congress of Mathematicians The International Congress of Mathematicians (ICM) is the largest conference for the topic of mathematics. It meets once every four years, hosted by the International Mathematical Union (IMU). The Fields Medals, the IMU Abacus Medal (known before ...
in 1924 in Toronto, in 1932 in Zürich, and in 1936 in Oslo. In 1932 he participated in the Congresul Matematicienilor Români in
Drobeta-Turnu Severin Drobeta-Turnu Severin (), colloquially Severin, is a city in Mehedinți County, Oltenia, Romania, on the northern bank of the Danube, close to the Iron Gates. It is one of six Romanian county seats List of cities and towns on the river Danube, lyin ...
. In 1935 he gave a talk at the inaugural Congrés International des Récréations Mathématiques in Brussels. His doctoral students include Guy Hirsch.


Selected publications

* ''Un théorème sur les liaisons'', 1923 * ''Periodico matematico'', 1927 * ''Analysis situs: un problème d’énumération'', Brüssel, M. Lamertin 1931 * ''Sur un problème de géométrie infinitésimale'', Brüssel, M. Lamertin 1932


References


External links

* ''Flemish'' {{DEFAULTSORT:Errera, Alfred 20th-century Belgian mathematicians Belgian mathematicians 1886 births 1960 deaths