Expressiveness of Restricted Recursive Queries (Extended Abstract)

  title={Expressiveness of Restricted Recursive Queries (Extended Abstract)},
  author={Foto N. Afrati and Stavros S. Cosmadakis},
We study the effect of various syntactic restrictions on the expressive power of database logic programs. We find natural examples of programs which<list><item>require recursively defined predicates of arbitrarily large width, </item><item>require rules with arbitrarily many recursive calls, or </item><item>require nonlinear rules, but can be evaluated in <italic>NC</italic><supscrpt>2</supscrpt>. </item></list>