Multilevel hierarchical retrieval

As large databases of conceptual graphs are developed for complex domains, eecient retrieval techniques must be developed to manage the complexity of graph-matching while maintaining reasonable space requirements. This paper describes a novel method \the multi-level hierarchical retrieval method" that exploits redundancy to improve both space and execution time eeciency. The method involves search in multiple partially ordered (by \more-general-than") hierarchies such that search in a simpler hierarchy reduces the search time in the hierarchy of next complexity. The speciic hierarchies used are: the traditional partial order over conceptual graphs; a partial order over node descriptors; a partial order over \descriptor units"; and nally, the simplest partial order is the traditional type hierarchy.