Ronald Jensen (mathematician)

Jensen at the First European Set Theory Meeting, Będlewo, Poland, 2007

Ronald Björn Jensen (born April 1, 1936 in Charlottesville , Virginia ) is an American mathematician who deals with axiomatic set theory and mathematical logic .

Jensen studied economics from 1954 to 1959 at the American University in Washington, DC and then until 1964 mathematics at the University of Bonn , where he received his doctorate in 1964 under Gisbert Hasenjaeger . He then worked as an assistant in Bonn until 1969, where he completed his habilitation in 1967 . From 1969 to 1975 he was a professor at the University of Oslo and taught at the same time at Rockefeller University in New York (until 1971) and at the University of California, Berkeley (until 1973). From 1974 to 1975 he was a Humboldt Prize winner at the University of Bonn, where he was also a professor from 1976 to 1978. 1978/79 he was visiting scholar at Oxford University , 1979 to 1981 professor at the University of Freiburg im Breisgau . From 1981 to 1994 he was a Senior Research Fellow at All Souls College, Oxford University. From 1994 until his retirement in 2001 he was professor for mathematical logic at the Humboldt University in Berlin . He lives in Berlin.

Jensen researched axiomatic set theory, especially the theory of large cardinal numbers and internal models such as Kurt Gödel's constructive universe . For The fine structure of the constructible hierarchy , (Annals of Mathematical Logic, Vol. 4, 1972, pp. 229-308) he received the 2003 Leroy P. Steele Prize . The work was groundbreaking for the development of inner models, for which Jensen provided new constructions depending on assumptions about the existence of large cardinal numbers. His coverage theorem says that if the number Zero Sharp ( ) does not exist, uncountable infinite sets of ordinals can be covered by constructible sets of equal thickness. Jensen revealed the existence of various nuclear models (core models), as the Dodd-Jensen-core model for non-existence of a measurable cardinal. He also found various combinatorial principles ( diamonds , squares , morass) in internal models that were also used in other areas of mathematics. He is also known for his coding theorem (proven in Coding the Universe 1982). ${\ displaystyle 0 ^ {\ #}}$

In 1990 he was the first Gödel lecturer . In 2001 he gave the Tarski Lectures . In 2015 he received the Hausdorff Medal of the European Set Theory Society with John R. Steel for her work K without the measurable .

Fonts

Set theory models. Consistency and independence of the continuum hypothesis and the axiom of choice. (Lecture Notes in Mathematics; Vol. 37). Springer, Berlin 1967.
Coding the Universe. Cambridge University Press, Cambridge 1982, ISBN 0-521-28040-0 (with Aaron Beller and Philip Welch).
with Anthony J. Dodd : The core model, Annals of Mathematical Logic, Volume 20, 1981, pp. 43-75
with Anthony J. Dodd: The covering lemma for K, Annals of Mathematical Logic, Volume 22, 1982, pp. 1-30
with John R. Steel: K without the measurable , The Journal of Symbolic Logic, Volume 78, 2013, pp. 708-734

Web links

Individual evidence

↑ Hausdorff Medal in 2015, ESTS

personal data
SURNAME	Jensen, Ronald
ALTERNATIVE NAMES	Jensen, Ronald Björn (full name)
BRIEF DESCRIPTION	American mathematician
DATE OF BIRTH	April 1, 1936
PLACE OF BIRTH	Charlottesville , Virginia

[1] Hausdorff Medal in 2015, ESTS