Querying Contextualized Information Bases

The notion of context appears in several disciplines, including computer science, in various forms. In this paper, we are concerned with a notion of context in the area of information bases. First, we present a general definition whereby a context is seen as a set of objects, within which each object has a set of names and possibly a reference: the reference of the object is another context which "hides" detailed information about the object. Then, we address issues concerning manipulation of information as organized in our context model. In particular, we focus on the following issues: (i) accessing information in the context structure using paths of names, or paths of references, (ii) retrieval of contextualized information by defining useful fundamental query operations on contexts such as select, project, generate (which allows the reorganization of context structures), and path select. Finally, we illustrate the usefulness of our contextualization mechanism by presenting higher level query operations that enable users to explore a contextualized information base. These higher level operations include focusing on a context of interest, searching the context structure for a specific information, and making cross references of an object from one context to another in order to obtain alternative representations of that object.