Greg Hjorth

Gregory Hjorth (also: Greg Hjorth, born June 14, 1963 in Melbourne, † January 13, 2011 same place ) was an Australian logician who worked on algebra, axiomatic set theory, and especially with descriptive set theory.

Hjorth, the son of a neurologist from Melbourne. He studied mathematics and philosophy in Melbourne and his PhD in 1993 at the University of California, Berkeley in W. Hugh Woodin ( The influence of). For his doctoral thesis on descriptive set theory the bag Prize for got " their surprising consequences for the relationship of projective quantities and large cardinals " ( eulogy ). He was a professor at the California Institute of Technology (Caltech ), the University of California, Los Angeles ( UCLA) and most recently a professor at the University of Melbourne.

In 2003 he received the Karp Prize with Alexander S. Kechris for her work on Borel equivalence relations, especially countable Borel equivalence relations and applications in the theory of turbulence. In 2010 he held the Tarski Lectures.

In 1998 he was invited speaker at the International Congress of Mathematicians in Berlin (When is an equivalence relation classifiable? ).

Had his work in descriptive set theory also related to ergodic theory to group theory and the theory of automatic structures.

Hjorth was an accomplished chess player. In 1983 he was Commonwealth champion. From 1984 he was an International Master. He was an atheist and a vegan.

On January 13, 2011 Hjorth died of a heart attack.

Writings

• Alexander S. Kechris with: Rigidity theorems for actions of product groups and countable Borel equivalence relations, Memoirs of the AMS, 2005
• Greg Hjorth: Borel equivalence relations. In Matthew Foreman, Akihiro Kanamori (eds.): Handbook of Set Theory. Springer, 2010, ISBN 978-1-4020-4843-2, doi: 10.1007/978-1-4020-5764-9 (online, accessed on 30 October 2012).