Sy Friedman

Sy-David Friedman (born May 23, 1953 in Chicago) is an American and Austrian mathematician and a professor of mathematics at the University of Vienna and the director of the Kurt Gödel Research Center for Mathematical Logic. His main research interest lies in mathematical logic, in particular in set theory and recursion theory.
Friedman is the brother of mathematician Harvey Friedman.

He studied at Northwestern University and, from 1970, at the Massachusetts Institute of Technology. He received his Ph.D. in 1976 from MIT (his thesis Recursion on Inadmissible Ordinals was written under the supervision of Gerald E. Sacks).

In 1979 Sy Friedman accepted a position at MIT, and in 1990 he became a full professor there. Since 1999 he has been a professor of mathematical logic at the University of Vienna. He is a Fellow of Collegium Invisibile.

He authored about 70 research articles, including:

• Friedman, Sy D. (1981). "Negative solutions to Post's problem. II". Annals of Mathematics. Second Series. The Annals of Mathematics, Vol. 113, No. 1. 113 (1): 25–43. doi:10.2307/1971132. JSTOR 1971132. 
• Friedman, Sy (1985). "A guide to "Coding the Universe" by Beller, Jensen, Welch". Journal of Symbolic Logic. The Journal of Symbolic Logic, Vol. 50, No. 4. 50 (4): 1002–1019. doi:10.2307/2273986. JSTOR 2273986. 
• Friedman, Sy D. (1990). "The ${\displaystyle \Pi _{2}^{1}}$-singleton conjecture". J. Amer. Math. Soc. 3 (4): 771–791. doi:10.1090/S0894-0347-1990-1071116-6. 
• Friedman, Sy D (2005). "Genericity and large cardinals". J. Math. Log. 5 (2): 149–166. doi:10.1142/S0219061305000420. 

He also published a research monograph

• Friedman, Sy D. (2000). Fine structure and class forcing. de Gruyter Series in Logic and its Applications. 3. Berlin: Walter de Gruyter & Co. ISBN 3-11-016777-8.