Principal members are:
Research in qualitative reasoning investigates the non-quantitative representations and inference processes involved in what is sometimes termed commonsense reasoning about complex systems. Such reasoning is prevalent in everyday thought about physical systems. For example, if I throw a ball up in the air it will go up, stop, fall down, hit the floor and bounce back up, repeating the previous process; this will continue for several cycles, rising less each time due to the loss of energy in the bouncing process. What are the basic elements of qualitative models of such situations and how are these models used to produce projections into the future of the impacts of actions?
We have investigated qualitative reasoning in two domains: alternating current circuit theory and economics. In circuit theory we have been interested in two primary questions. The first is: how do non-linear circuit elements impact a qualitative circuit model? We capture this as model specialization based on the current states of such devices. As the non-linear components change state, the circuit model must be modified; this can include a reclustering of elements as parts of the circuit become effectively disconnected. The second problem is: how can we capture the steady-state behavior of alternating current circuits? We developed a method based on the notion of phasors, allowing us to solve control and diagnostic problems changes in phase angles between currents and voltages.
In economics, we have explored the application of qualitative market models to the simulation of complex, multi-market economic systems. A qualitaive market model is a mechanism that adjusts a control variable associated with the market in the direction necessary to restore market equilibrium. Multiple-markets interact as variables in one market can be viewed as parameters to others. How to efficiently and effectively simulate, and thus predict the impacts of, changes to a multiple-market system parameter was one focus of this work.
References
Farley, A.M. and Lin, K.P., "Qualitative reasoning in economics", Journal of Economic Dynamics and Control, 14, p465-490, (1990).
Lin, K.P. and Farley, A.M., "Qualitative economic reasoning: A disequilibrium perspective", Computer Science in Economics and Management, 4, p117-133, (1991).
Liu, Z.Y. and Farley, A.M., "Tasks, Models, Perspectives, and Dimensions", Proc. Fifth International Workshop on Qualitative Physics, Austin, Texas, p1-9, (1991).
Liu, Z.Y. and Farley, A.M., "Structural aggregation in commonsense reasoning", Proceedings of the National Conference on Artificial Intelligence (AAAI-91), p868-873, (1991).
J. Flores and Farley, A.M. "Incremental Design for Linear Circuits", Proceedings of International Workshop on Qualitative Reasoning, QR-98, Boston, MA, (1998).
J. Flores and Farley, A.M, "Reasoning About Circuits: A Model-Based Approach", in AI Communications, (1999).
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