RATIONALE

"Marcus, VT"

S. Marcus, J. Stout & J. McDermott, VT: An Expert Elevator Designer
That Uses Knowledge-Based Backtracking. In: Artificial Intelligence in
Engineering Design, Vol. 1, (Eds) C. Tong & D. Sriram, Academic Press,
1992, pp. 317-355. 



VT was a highly influential configuration design system working in a
realistic domain that affected research on knowledge acquisition,
configuration, and task-specific but domain-independent reasoning.  It
is characterized by a single level of reasoning driven by incremental
refinements to the growing configuration, with contraints checking the
correctness, and failures handled by ordered lists of suggested
fixes. The system is able to detect the potential for mutually
incompatible fixes (e.g., fixing contraint A's failure causes
constraint B's failure, and vice versa).