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Decompositional Modeling through Caricatural Reasoning
 In Proceedings of AAAI94
, 1994
"... Many physical phenomena are sufficiently complex that the corresponding equations afford little insight, or no analytical method provides an exact solution. Decompositional modeling (DM) captures a modeler's tacit skill at solving nonlinear algebraic systems. DM divides statespace into a patchwork ..."
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Cited by 12 (7 self)
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Many physical phenomena are sufficiently complex that the corresponding equations afford little insight, or no analytical method provides an exact solution. Decompositional modeling (DM) captures a modeler's tacit skill at solving nonlinear algebraic systems. DM divides statespace into a patchwork of simpler subregimes, called caricatures, each of which preserves only the dominant characteristics of that regime. It then solves the simpler nonlinear system and identifies its domain of validity. The varying patchwork reflects how variations in the parameters change the dominant characteristics. The patchwork is built by extracting equational features consisting of the relative strength of terms, and then exagerating and merging these features in different combinations, resulting in the different caricatural regimes. DM operates by providing strategic guidance to a pair of symbolic manipulation systems for qualitative sign and order of magnitude algebra. The approach is sufficient to re...
HigherOrder Derivative Constraints in Qualitative Simulation
 Artificial Intelligence
, 1991
"... Qualitative simulation is a useful method for predicting the possible qualitatively distinct behaviors of an incompletely known mechanism described by a system of qualitative differential equations (QDEs). Under some circumstances, sparse information about the derivatives of variables can lead to in ..."
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Cited by 7 (3 self)
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Qualitative simulation is a useful method for predicting the possible qualitatively distinct behaviors of an incompletely known mechanism described by a system of qualitative differential equations (QDEs). Under some circumstances, sparse information about the derivatives of variables can lead to intractable branching (or "chatter") representing uninteresting or even spurious distinctions among qualitative behaviors. The problem of chatter stands in the way of real applications such as qualitative simulation of models in the design or diagnosis of engineered systems. One solution to this problem is to exploit information about higherorder derivatives of the variables. We demonstrate automatic methods for identification of chattering variables, algebraic derivation of expressions for secondorder derivatives, and evaluation and application of the sign of second and thirdorder derivatives of variables, resulting in tractable simulation of important qualitative models. Caution is requir...
Methods of Modeling and Assisting Causal Understanding in Physical Systems
 In: UM96  Proceedings of the Fifth International Conference on User Modeling
, 1996
"... This paper presents methods for modeling and assisting students ' understanding about causalities between physical quantities based on comparative reasoning. Our tutoring system discusses causalities in an object system with the student by choosing dialogue strategies according to student's understa ..."
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Cited by 3 (0 self)
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This paper presents methods for modeling and assisting students ' understanding about causalities between physical quantities based on comparative reasoning. Our tutoring system discusses causalities in an object system with the student by choosing dialogue strategies according to student's understanding states. The student's understanding state is represented by the causal network and table. Dialogue strategies are characterized by the following four elements of dialogue; selection of topic, progress of dialogue, granularity of dialogue, and style of utterance. This paper also presents a method of deepening student's understanding of the object system by comparing it with a similar system which is generated by partitioning or simplifying the original system. The partitioned system has a different causality from the original system, and the simplified system has a similar causality to the original system. Introduction This paper presents methods of how an intelligent tutoring system ...
The Thought Experiment Approach to Qualitative Physics
 Proc. IJCAI89
, 1989
"... This paper discusses the application of the thought experiment methodology to qualitative reasoning. Problem solving using this technique involves simplification of the original problem, solution of the simplified problem, and generalization of the results obtained. Our emphasis in this work is to d ..."
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Cited by 2 (2 self)
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This paper discusses the application of the thought experiment methodology to qualitative reasoning. Problem solving using this technique involves simplification of the original problem, solution of the simplified problem, and generalization of the results obtained. Our emphasis in this work is to demonstrate the effectiveness of this approach in addressing complexity and grain size issues that affect qualitative simulation. The thought experiment methodology is presented formally, the implementation of a problem solver called TEPS is briefly discussed, and the methodology is compared with related techniques such as approximation, aggregation, and exaggeration. 1