Daniel Berleant and Benjamin Kuipers. 1997.

**Qualitative and quantitative simulation: bridging the gap**.

Artificial Intelligence **95**(2): 215-255, 1997.

Shortcomings of qualitative simulation and of quantitative simulation
motivate combining them to do simulations exhibiting the strengths of
both. The resulting class of techniques is called
*semi-quantitative simulation*. One approach to
semi-quantitative simulation is to use numerical intervals to represent
incomplete quantitative information. In this research we demonstrate
semi-quantitative simulation using intervals in an implemented
semi-quantitative simulator called Q3. Q3 progressively refines a
qualitative simulation, providing increasingly specific quantitative
predictions which can converge to a numerical simulation in the limit
while retaining important correctness guarantees from qualitative and
interval simulation techniques.

Q3's simulations are based on a technique we call *step-size
refinement*. While a pure qualitative simulation has a very coarse
step size, representing the state of a system trajectory at relatively
few qualitatively distinct states, Q3 interpolates newly explicit
states between distinct qualitative states, thereby representing more
states which instantiate new constraints, leading to improved
quantitative inferences.

Q3's techniques have been used for prediction, measurement interpretation, diagnosis, and even analysis of the probabilities of qualitative behaviors. Because Q3 shares important expressive and inferential properties of both qualitative and quantitative simulation, Q3 helps to bridge the gap between qualitative and quantitative simulation.

[QR home: http://www.cs.utexas.edu/users/qr] BJK