A broad class of first-order rewritable tuple-generating dependencies

Abstract

We study reasoning, and in particular query answering, over databases with tuple-generating dependencies (TGDs). Our focus is on classes of TGDs for which conjunctive query answering is first-order rewritable, i.e., can be reduced to the standard evaluation of a first-order query over the database. In this paper, we define the class of weakly recursive TGDs, and prove that this class comprises and generalizes every previously known FOL-rewritable class of TGDs, under fairly general assumptions on the form of the TGDs. © 2012 Springer-Verlag.