Qualitative simulation is a well-known reasoning technique that involves the use of simulation technologies. Reasoning is made to\ndetermine qualitative values and change directions of system variables, and it is done for each time point and time interval following\nthe time point. Qualitative variables possess continuous qualitative value sets that are discretized by landmark points. Qualitative\nsimulation uses qualitative time representation and its quantitative value is of no interest. The main purpose of this study was to\ndevelop a technique to determine time steps for a quantitative simulation under guidance of qualitative information. The proposed\ntechnique determined time advances using qualitative and quantitative information together to obtain a robust time step as wide as\npossible for simulation time advances. For this purpose, sign algebraic properties and derivation roots of quantitative equations and\nqualitative variable values with their change directions were used to compute time advances. In the approach, qualitative simulation\ndetermined landmark points to be advanced, and quantitative simulation calculated the duration required. Using the proposed\nalgorithm, the simulation is advanced instead of iterating simulation time for a predefined time step and checking whether or not\nthere is any activity in the interval, directly to the time points that are qualitatively different.
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