| A Hierarchy of Turing Degrees: A Transfinite Hierarchy of Lowness Notions in the Computably Enumerable Degrees, Unifying Classes, and Natural Definability (AMS-206) Rod Downey and Noam Greenberg are professors of mathematics at Victoria University of Wellington in New Zealand. Downey is the coauthor of Parameterized Complexity , Algorithmic Randomness and Complexity , and Fundamentals of Parameterized Complexity . Greenberg is the author of The Role of True Finiteness in the Admissible Recursively Enumerable Degrees . |