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{{Infobox scientist | |||
| name = Ronald Jensen | |||
| image = RJensen.jpg | |||
| image_size = 200px | |||
| caption = Prof. Ronald Jensen giving a lecture during ''The First European Set Theory Meeting'', Będlewo ([[Poland]]), July 2007 | |||
| birth_date = {{Birth date and age|1936|4|1}} | |||
| birth_place = | |||
| residence = [[Berlin]], [[Germany]] | |||
| nationality = [[United States]] | |||
| ethnicity = | |||
| field = [[Mathematician]] | |||
| work_institution = [[Humboldt University of Berlin]] | |||
| alma_mater = [[University of Bonn]] | |||
| doctoral_advisor = Gisbert Hasenjaeger | |||
| doctoral_students = Stephen Abraham, Oliver Deiser, Gunter Fuchs, Peter Koepke, Michael Lakis, [[Benedikt Löwe|Benedikt Loewe]], Adrian Mathias, Charles Morgan, Ralf-Dieter Schindler, Max Schröder, Lee Stanley, Martin Zeman | |||
| known_for = [[Axiomatic Set Theory|Set theory]], [[mathematical logic]] | |||
| prizes = | |||
| footnotes = | |||
}} | |||
'''Ronald Björn Jensen''' (born April 1, 1936) is an [[United States|American]] [[mathematician]] active in [[Europe]], primarily known for his work in [[mathematical logic]] and [[set theory]]. | |||
==Career== | |||
Jensen completed the BA in [[economics]] at [[American University]] in 1959, and a Ph.D. in [[mathematics]] at the [[University of Bonn]] in 1964. His supervisor was [[:de:Gisbert Hasenjaeger|Gisbert Hasenjaeger]]. Jensen taught at [[Rockefeller University]], 1969–71, and the [[University of California, Berkeley]], 1971-73. The balance of his academic career was spent in Europe at the | |||
[[University of Bonn]], the [[University of Oslo]], the [[Albert Ludwigs University of Freiburg|University of Freiburg]], the [[University of Oxford]], and the [[Humboldt-Universität zu Berlin]], from which he retired in 2001. He now resides in [[Berlin]]. | |||
==Results== | |||
Jensen's better-known results include the: | |||
* [[Axiomatic set theory]] [[New Foundations|NFU]], a variant of [[New Foundations]] (NF) where extensionality is weakened to allow several sets with no elements, and the proof of NFU's [[consistency]] relative to [[Peano arithmetic]]; | |||
* Fine structure theory of the [[constructible universe]] '''L'''. This work led to his being awarded in 2003 the [[Leroy P Steele Prize|Leroy P. Steele Prize for Seminal Contribution to Research]] of the [[American Mathematical Society]] for his 1972 paper titled "The fine structure of the constructible hierarchy"; | |||
*Definitions and proofs of various [[Infinitary combinatorics|infinitary combinatorial principle]]s in '''L''', including [[diamondsuit|diamond]] <math>\diamondsuit</math>, [[global square|square]], and [[morass (set theory)|morass]]; | |||
* Jensen [[Covering Lemma]] for '''L'''; | |||
* General theory of [[core model]]s and the construction of the [[Dodd–Jensen core model]]; | |||
* Technique of [[coding the universe by a real]]. | |||
==External links== | |||
*Jensen's [http://www-irm.mathematik.hu-berlin.de/~raesch/org/jensen.html page] at the [[Humboldt-Universität zu Berlin]]. | |||
*[http://kgs.logic.at/index.php?id=42 Brief biographies] of past presidents of the [[Kurt Gödel Society]]. | |||
{{Persondata | |||
| NAME = Jensen, Ronald | |||
| ALTERNATIVE NAMES = | |||
| SHORT DESCRIPTION = American logician | |||
| DATE OF BIRTH = April 1, 1936 | |||
| PLACE OF BIRTH = | |||
| DATE OF DEATH = | |||
| PLACE OF DEATH = | |||
}} | |||
{{DEFAULTSORT:Jensen, Ronald}} | |||
[[Category:1936 births]] | |||
[[Category:Living people]] | |||
[[Category:American logicians]] | |||
[[Category:20th-century mathematicians]] | |||
[[Category:21st-century mathematicians]] | |||
[[Category:American University alumni]] | |||
[[Category:Set theorists]] | |||
[[Category:University of Bonn alumni]] | |||
Revision as of 15:56, 23 March 2013
Template:Infobox scientist Ronald Björn Jensen (born April 1, 1936) is an American mathematician active in Europe, primarily known for his work in mathematical logic and set theory.
Career
Jensen completed the BA in economics at American University in 1959, and a Ph.D. in mathematics at the University of Bonn in 1964. His supervisor was Gisbert Hasenjaeger. Jensen taught at Rockefeller University, 1969–71, and the University of California, Berkeley, 1971-73. The balance of his academic career was spent in Europe at the University of Bonn, the University of Oslo, the University of Freiburg, the University of Oxford, and the Humboldt-Universität zu Berlin, from which he retired in 2001. He now resides in Berlin.
Results
Jensen's better-known results include the:
- Axiomatic set theory NFU, a variant of New Foundations (NF) where extensionality is weakened to allow several sets with no elements, and the proof of NFU's consistency relative to Peano arithmetic;
- Fine structure theory of the constructible universe L. This work led to his being awarded in 2003 the Leroy P. Steele Prize for Seminal Contribution to Research of the American Mathematical Society for his 1972 paper titled "The fine structure of the constructible hierarchy";
- Definitions and proofs of various infinitary combinatorial principles in L, including diamond , square, and morass;
- Jensen Covering Lemma for L;
- General theory of core models and the construction of the Dodd–Jensen core model;
- Technique of coding the universe by a real.
External links
- Jensen's page at the Humboldt-Universität zu Berlin.
- Brief biographies of past presidents of the Kurt Gödel Society.