# Alfred Errera

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{{short description|Belgian mathematician}}
'''Alfred Errera''' (1886 – 1960) was a Belgian [mathematician](/source/mathematician).<ref>Errera-Bourla, Milantia, ''Une histoire juive. Les Errera. Parcours d'un assimilation'', Brussels: Éditions Racine, 2000, hoofdstuk VIII, "Alfred, le mathématicien", pp. 169–200</ref>

Errera studied at the [Université libre de Bruxelles](/source/Universit%C3%A9_libre_de_Bruxelles), where he received his [Ph.D.](/source/Ph.D.) in 1921 with dissertation ''Du coloriage des cartes et de quelques questions d'analysis situs''.<ref>{{MathGenealogy|id=46692}}</ref> In his dissertation he introduced what is now called the [Errera graph](/source/Errera_graph),<ref>[http://mathworld.wolfram.com/ErreraGraph.html Errera Graph, Mathworld]</ref> which is a counterexample to the validity of the alleged proof of the four color theorem by [Alfred Kempe](/source/Alfred_Kempe). From 1928 to 1956 he was a professor at the Université libre de Bruxelles.

He did research on [topology](/source/topology), especially the theory of [polyhedra](/source/polyhedra) and the [Jordan curve theorem](/source/Jordan_curve_theorem). With [Théophile Lepage](/source/Th%C3%A9ophile_Lepage) he conducted a seminar on analysis at the University of Brussels.

During World War I, he worked on the [acoustic source localization](/source/acoustic_source_localization) of artillery fire and from 1921 to 1938 taught courses on this subject at the [Royal Military Academy](/source/Royal_Military_Academy_(Belgium)).

Errera was an Invited Speaker at the [International Congress of Mathematicians](/source/International_Congress_of_Mathematicians) in 1924 in Toronto, in 1932 in Zürich, and in 1936 in Oslo.<ref>{{Cite web |url=http://www.mathunion.org/db/ICM/Speakers/Search.php |title=ICM Plenary and Invited Speakers since 1897 |access-date=2016-08-05 |archive-url=https://web.archive.org/web/20140219112750/http://www.mathunion.org/db/ICM/Speakers/Search.php |archive-date=2014-02-19 |url-status=dead }}</ref> In 1932 he participated in the Congresul Matematicienilor Români in [Drobeta-Turnu Severin](/source/Drobeta-Turnu_Severin). In 1935 he gave a talk at the inaugural Congrés International des Récréations Mathématiques in Brussels. His doctoral students include [Guy Hirsch](/source/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==
{{Reflist}}

==External links==
*{{cite web|url=http://www.dbnl.org/tekst/hall014gesc02_01/hall014gesc02_01_0034.php|title=Geschiedenis van de wetenschappen in België. 1815–2000 • dbnl|author=Despy-Meyer, A.|author2=Halleux, R.|author3=Vandersmissen, J.|author4=Vanpaemel, G.|year=2001}} ''Flemish''

{{Authority control}}

{{DEFAULTSORT:Errera, Alfred}}
Category:20th-century Belgian mathematicians
Category:Belgian mathematicians
Category:1886 births
Category:1960 deaths

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