Leo Harrington
Leo Anthony Harrington is a professor of mathematics at the University of [California, Berkeley] who works in computability theory, model theory, and set theory.
His notable results include proving the Paris–Harrington theorem along with Jeff [Paris (mathematician)|Jeff Paris],
showing that if the axiom of determinacy holds for all analytic sets then x# exists for all reals x,
and proving with Saharon Shelah that the first-order theory of the partially [ordered set] of computably enumerable Turing degrees is undecidable.