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Abstract.

We show that qualitative simulation algorithms can make better use of their input to deduce significant amounts of information about the relative lengths of the time intervals in their output behavior predictions.

 Simple techniques employing concepts like symmetry, periodicity, and comparison of the circumstances in two time intervals can enable the reasoner to build a list of facts representing the deduced information about relative durations. These facts are used by new filters, which eliminate proposed spurious behaviors leading to inconsistent duration data. Surviving behaviors are annotated with richer descriptions of the qualitative properties of system variables, in addition to the extracted relative duration information. For some of the filters, we prove that they are the best ones among the possible filters that use the same information.

 For the purpose of developing these filters and proving that they are sound, we propose a new sign algebra SR1* by extending the existing sign algebras S1 and SR1 and a new Comparative Analysis Method, Comparison Calculus, which can be used  not only to design filters that eliminate spurious behaviors, but also to solve Comparison Analysis Problems.