Gregory Hjorth

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Gregory "Greg" Hjorth (born June 14, 1963 in Melbourne ; † January 13, 2011 ibid) was an Australian logician who dealt with algebra, axiomatic set theory and, in particular, descriptive set theory.

Scientific work and life

Hjorth, the son of a neurologist from Melbourne, studied mathematics and philosophy in Melbourne and received his doctorate in 1993 from the University of California, Berkeley under W. Hugh Woodin ( The influence of ). For his dissertation on descriptive set theory, he received the Sacks Prize for "its surprising consequences for the relationship between projective sets and large cardinal numbers " (laudation). He was a professor at the California Institute of Technology (Caltech), the University of California, Los Angeles (UCLA) and most recently professor at the University of Melbourne .

In 1997 he received a research grant from the Alfred P. Sloan Foundation ( Sloan Research Fellowship ). In 2003 he received the Karp Prize with Alexander S. Kechris for her work on Borel equivalence relations, specially countable Borel equivalence relations and applications in the theory of turbulence . In 2010 he gave the Tarski Lectures .

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

His work in descriptive set theory was also related to ergodic theory , group theory and the theory of automatic structures .

He was an atheist and a vegan .

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

chess

Hjorth was an accomplished chess player who was eligible to play for the Australian Chess Federation until 2000, and since then for the United States Chess Federation . In 1983 he became Commonwealth Champion, in 1984 he was named International Champion . Hjorth took part with the Australian national team in the 1984 and 1986 Chess Olympiads (in addition, he had already been nominated for the 1982 Chess Olympiad as a second reserve player, but remained unused). Hjorth's last Elo rating was 2378 and his highest rating of 2440 was reached in July 1984.

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Web links

Individual evidence

  1. ↑ Gregory Hjorth in the Mathematics Genealogy Project (English)Template: MathGenealogyProject / Maintenance / id used
  2. ↑ Laudation Sacks Prize ( Memento of the original from March 11, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.aslonline.org
  3. ↑ a b Alexander S. Kechris: In Memoriam: Greg Hjorth . In: The Bulletin of Symbolic Logic . tape 17 , no. 3 , September 2011, p. 471-477 , doi : 10.2178 / bsl / 1309952323 ( online [accessed October 30, 2012]).
  4. ↑ Greg Hjorth, Bakh Khoussainov, Antonio Montalbán and Andre Nies: From Automatic Structures to Borel Structures . In: LICS '08 Proceedings of the 2008 23rd Annual IEEE Symposium on Logic in Computer Science . ISBN 978-0-7695-3183-0 , pp. 431–441 , doi : 10.1109 / LICS.2008.28 ( online [PDF; 219 kB ; accessed on October 30, 2012]).
  5. ^ In the loving memory of Greg Hjorth. (PDF; 916 kB) (No longer available online.) Archived from the original on June 28, 2011 ; Retrieved October 30, 2012 (obituaries on the UCLA website (including from mathematicians and a chess player)).
  6. ↑ In memoriam: Greg Hjorth, Professor of Mathematics, 1963 - 2011. (No longer available online.) Archived from the original on September 30, 2011 ; Retrieved October 30, 2012 .
  7. ↑ Newsletter April 2011. (PDF; 108 kB) Association for Symbolic Logic , accessed on October 30, 2012 .
  8. ↑ Guy Rundle: Australia loses a world-class maths wizard and chess champ. The Age , February 7, 2011, accessed October 30, 2012 .
  9. ↑ a b Gregory Hjorth's Elo development up to 2001 on olimpbase.org (English)
  10. ↑ Gregory Hjorth's results at the Chess Olympiads on olimpbase.org (English)
  11. ↑ Gregory Hjorth's Elo development from 2000 to 2011 on benoni.de
personal data
SURNAME Hjorth, Gregory
ALTERNATIVE NAMES Hjorth, Greg
BRIEF DESCRIPTION Australian logician
DATE OF BIRTH June 14, 1963
PLACE OF BIRTH Melbourne
DATE OF DEATH January 13, 2011
Place of death Melbourne