Date of this Version
We show that a form of divide and conquer recursion on sets together with the relational algebra expresses exactly the queries over ordered relational databases which are NC-computable. At a finer level, we relate k nested uses of recursion exactly to ACk, k ≥ 1. We also give corresponding results for complex objects.
Dan Suciu and Val Tannen, "A Query Language for NC", . February 1994.
Date Posted: 25 July 2007