Gerald Sacks

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Gerald Enoch Sacks (born 1933, Brooklyn) is a logician who holds a joint appointment at Harvard University as a professor of mathematical logic and the Massachusetts Institute of Technology as a professor emeritus.[1][2] His most important contributions have been in recursion theory. Named after him is Sacks forcing, a forcing notion based on perfect sets[3] and the Sacks Density Theorem, which asserts that the partial order of the recursively enumerable Turing degrees is dense.[4]

Sacks earned his Ph.D. in 1961 from Cornell University under the direction of J. Barkley Rosser, with a dissertation entitled 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.[5]

Selected publications[edit]

  • Degrees of unsolvability, Princeton University Press 1963, 1966[6]
  • Saturated Model Theory, Benjamin 1972; 2nd edition, World Scientific 2010[7]
  • Higher Recursion theory, Springer 1990[8]
  • Selected Logic Papers, World Scientific 1999[9]
  • Mathematical Logic in the 20th Century, World Scientific 2003


  1. ^ Short CV, retrieved 2015-06-26.
  2. ^ "Professor Gerald Sacks Retires from MIT" (PDF), Integral: News from the Mathematics Department at MIT, 1: 6, Autumn 2006.
  3. ^ Halbeisen, Lorenz J. (2011), Combinatorial Set Theory: With a Gentle Introduction to Forcing, Springer Monographs in Mathematics, Springer, pp. 380–381, ISBN 9781447121732.
  4. ^ 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.
  5. ^ Gerald Sacks at the Mathematics Genealogy Project
  6. ^ Review of Degrees of unsolvability by Kenneth Appel, MR0186554
  7. ^ Review of Saturated model theory by P. Stepanek, MR0398817
  8. ^ Review of Higher recursion theory by Dag Normann, MR1080970
  9. ^ Review of Selected logic papers by Dag Normann, MR1783306