On the problem of degeneration of linear systems by high gain

The authors construct two examples to show that when the gain goes to infinity as a point on the Grassmannian, A specified closed loop system can degenerate, under different conditions, to: (1) a singular system with a unique solution or (2) a singular system with no unique solution. They observe that in case (1) the degeneration into the reduced system is robust whereas in case (2) it is not robust.<
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