A theory of command language dialogue for a knowledge-based human-computer interaction

The flexibility and usability of graphic-based HCIs can be increased by adding a natural language interface with command menus. Among the several other advantages, such embellishment offers the user an opportunity for direct expression of his or her behaviors, goals, intentions, and objectives along the continuum of the task knowledge. The existing graphic-based HCIs that operate on active symbologies and icons assume the user's mental models to correlate with perceptual and cognitive levels of the task understanding. This obviously increases mental loads and the frustration of the human adapting to the system. In reality, the system should be designed to adapt to the user's behavior and skill level. In order to improve the current design of graphic-based HCIs, we have formulated theories of command production language that will enhance the user's ability to interact with the system. The methods developed combine the theory of expert database with formal grammar to develop command-production rules using a natural language dictionary prototype. We show that the commands are linear, regular, and symmetric, although conforming to the formal rules of grammar.