[FOM] Gerald Sacks

[Harvey Friedman]

Gerald E. Sacks, my thesis advisor, died October 4 at the age of 86,
after a long illness. He was a pioneer in recursion theory, and is
particularly noted for his celebrated Sacks Density Theorem (there is
an r.e. degree strictly between any two different comparable r.e.
degrees) and Sacks forcing (forcing with perfect trees, which he used
to construct models of ZFC with a minimal degree of
nonconstructibility).

Gerald was honored In 1994, when the Association of Symbolic Logic
established the Sacks Prize in his name, which is awarded annually for
the most outstanding doctoral dissertation in mathematical logic.

Gerald supervised over 30 students, several of whom are among the most
visible logicians in the world.

Harvey Friedman