I graduated from Reed College in Portland, Oregon with a BA in Mathematics in 1974. I did my graduate work in mathematics at the University of Chicago, where I received my SM in 1976 and my PhD, directed by Professor Robert I. Soare, in 1980. From 1980 to 1984, I was an HC Wang Assistant Professor in the Mathematics Department of Cornell University. From 1980 to 1981, I also had a National Science Foundation Postdoctoral Research Fellowship.

Since 1984, I have been at the University of Massachusetts at Boston, first in the Department of Mathematics and Computer Science, now in the Department of Computer Science, except for one sabbatical year and another sabbatical half year spent at Heidelberg University. I have been a full professor since 1995 and am currently Department Chair.

Research

My research interests are Computability Theory (also known as Recursion Theory) and Theoretical Computer Science. (See the Computability Theory Web Page for more information on Computability Theory.)

I have co-authored a book, Mathematical Foundations of Computer Science, Volume 1: Sets, Relations and Induction, published by Springer-Verlag in their Texts and Monographs in Computer Science series. Volume 2, Logical Foundations of Computer Science, is in preparation.

My articles have mostly dealt with the study of the computably enumerable (also known as recursively enumerable) sets and their degrees under various reducibilities.