In conventional Boolean retrieval systems, users have difficulty controlling the amount of output obtained from a given query. This paper describes the design of a user interface which permits gradual enlargement or refinement of the user's query by browsing through a graph of term and document subsets. This graph is obtained from a lattice automatically generated from the usual document-term relation. The major design features of the proposed interface are the integration of menu, fill-in the blank and direct manipulation modes of interaction within the “fisheye view” [Furnas, 1986] paradigm. A prototype user interface incorporating some of these ideas has been implemented on a microcomputer.

The resulting interface is well adapted to various kinds of users and needs. More experienced users with a particular subject in mind can directly specify a query which results into a jump to a particular vertex in the graph. From there, the user can refine his initial query by browsing through the graph from that point on. On the other hand, casual users without any prior knowledge of the contents of the system or users without any particular subject in mind can freely navigate through the graph without ever specifying any query.