Gerald Sacks

Gerald Enoch Sacks (1933 – October 4, 2019) was an American logician whose most important contributions were in recursion theory. Named after him is Sacks forcing, a forcing notion based on perfect sets[1] and the Sacks Density Theorem, which asserts that the partial order of the recursively enumerable Turing degrees is dense.[2] Sacks had a joint appointment as a professor at the Massachusetts Institute of Technology and at Harvard University starting in 1972 and became emeritus at M.I.T. in 2006 and at Harvard in 2012.[3][4][5]

Sacks was born in Brooklyn in 1933. He earned his Ph.D. in 1961 from Cornell University under the direction of J. Barkley Rosser, with his dissertation On Suborderings of Degrees of Recursive Insolvability. Among his notable students are Lenore Blum, Harvey Friedman, Sy Friedman, Leo Harrington, Richard Shore, Steve Simpson and Theodore Slaman.[6]

  1. ^ Halbeisen, Lorenz J. (2011), Combinatorial Set Theory: With a Gentle Introduction to Forcing, Springer Monographs in Mathematics, Springer, pp. 380–381, ISBN 9781447121732.
  2. ^ Soare, Robert I. (1987), Recursively Enumerable Sets and Degrees: A Study of Computable Functions and Computably Generated Sets, Perspectives in Mathematical Logic, Springer, p. 245, ISBN 9783540152996.
  3. ^ Short CV, retrieved 2015-06-26.
  4. ^ "Professor Gerald Sacks Retires from MIT" (PDF), Integral: News from the Mathematics Department at MIT, 1: 6, Autumn 2006.
  5. ^ Chi Tat Chong, Yue Yang, "An interview with Gerald E. Sacks", Recursion Theory: Computational Aspects of Definability, ISBN 3110275643, 2015, p. 275
  6. ^ Gerald Sacks at the Mathematics Genealogy Project