Computer technology has yet to provide the modeling enterprise with adequate tools, with the results that modeling has become confused with simulation; modelers are artificially constrained to state-transition models; modelers cannot adequately deal with complex models; modelers often obtain numbers but not insight; and quantitative and qualitative models cannot be gracefully combined. Research that might alleviate these problems is discussed in this Note. A language must be developed that can smoothly express quantitative and qualitative notions in the context of a stand-alone model. The authors describe one small step in this direction: They model a little girl bouncing a ball, which involves both physical constraints and human decisionmaking, in a tightly intertwined manner. They also developed an illustrative language for expressing the model. This exercise demonstrated the importance of a stand-alone model and of the ability to smoothly combine qualitative and quantitative model elements. The need for improvement in automatic deduction is also discussed.
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