Ronald W. Ferguson and Kenneth D. Forbus, Northwestern University
A key problem in diagrammatic reasoning is understanding how people reason about qualitative relationships in diagrams. We claim that progress in diagrammatic reasoning is slowed by two problems: (1) researchers tend to start from scratch, creating new spatial reasoners for each new problem area, and (2) constraints from human visual processing are rarely considered. To address these problems, we created GeoRep, a spatial reasoning engine that generates qualitative spatial descriptions from line drawings. GeoRep has been successfully used in several research projects, including cognitive simulation studies of human vision. In this paper, we outline GeoRep’s architecture, explain the domain-independent and domain-specific aspects of its processing, and motivate the representations it produces. We then survey how GeoRep has been used in three different projects--a model of symmetry, a model of understanding juxtaposition diagrams of physical situations, and a system for reasoning about military courses of action.