  Conjunctive query answering over expressive Horn Description Logic ontologies
is a relevant and challenging problem which, in some cases, can be addressed by
application of the chase algorithm. In this paper, we define a novel acyclicity
notion which provides a sufficient condition for termination of the restricted
chase over Horn-SRIQ TBoxes. We show that this notion generalizes most of the
existing acyclicity conditions (both theoretically and empirically).
Furthermore, this new acyclicity notion gives rise to a very efficient
reasoning procedure. We provide evidence for this by providing a
materialization based reasoner for acyclic ontologies which outperforms other
state-of-the-art systems.
