For example, (Clarke et al., 2003) and (Lin et al., 2003) employ techniques for utilizing both unstruc-tured text and structured databases for question answering.
the approaches taken by both these systems differ from ours in that they enforce an order between the two strategies by attempting to locate answers in structured databases first for select question types and falling back to unstructured text when the former fails, while we explore both options in parallel and combine the results from multiple answering agents.