L´Hopital´s filter for QSIM

We have identified a source of spurious predictions inside the qualitative simulation algorithm QSIM. The algorithm fails to check for violations of l´Hopital´s rule, which causes the addition of inconsistent states to the behavior tree. Our proposed solution involves adding a new state filter to make the required controls and does not necessitate any additions or restrictions in the input set. We make use of extended corresponding value tuples spanning multiple constraints. The necessary modifications to the algorithm are explained and the technique is demonstrated on examples. Used in conjunction with other spurious behavior elimination methods, this approach would increase QSIM´s ability to handle more complex systems