Oliver M. Duschka , Alon Y. Levy , Recursive Plans for Information Gathering Proceedings of the 15th International Joint Conference on Artificial Intelligence 1997
Abstract: Generating query-answering plans for information gathering agents
requires to translate a user query, formulated in terms of a set of
virtual relations, to a query that uses relations that are actually
stored in information sources. Previous solutions to the translation
problem produced sets of conjunctive plans, and were therefore
limited in their ability to handle information sources with
binding-pattern limitations, and to exploit functional dependencies in
the domain model. As a result, these plans were incomplete w.r.t.
sources encountered in practice (i.e., produced only a subset of the
possible answers). We describe the novel class of recursive
information gathering plans, which enables us to settle two open
problems. First, we describe an algorithm for finding a query plan
that produces the maximal set of answers from the sources in the
presence of functional dependencies. Second, we describe an analogous
algorithm in the presence of binding-pattern restrictions in the
sources, which was not possible without recursive plans.