# Gerald Sacks

**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

- 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

## References

- ↑ Short CV, retrieved 2015-06-26.
- ↑ "Professor Gerald Sacks Retires from MIT" (PDF),
*Integral: News from the Mathematics Department at MIT*,**1**: 6, Autumn 2006. - ↑ Halbeisen, Lorenz J. (2011),
*Combinatorial Set Theory: With a Gentle Introduction to Forcing*, Springer Monographs in Mathematics, Springer, pp. 380–381, ISBN 9781447121732. - ↑ 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. - ↑ Gerald Sacks at the Mathematics Genealogy Project
- ↑ Review of
*Degrees of unsolvability*by Kenneth Appel, MR 0186554 - ↑ Review of
*Saturated model theory*by P. Stepanek, MR 0398817 - ↑ Review of
*Higher recursion theory*by Dag Normann, MR 1080970 - ↑ Review of
*Selected logic papers*by Dag Normann, MR 1783306