A new type of adaptive high-gain stabilizer for classes of linear time-invariant state-space systems is presented. The classes cover multi-input multi-output systems where the state dimension is not known. only standard assumptionj of minimum phase and known (respectively unknown) sign are requiied. The controller is of nondifferential form and ensures exponential de-cay of the trajectory. In the case where the sign of the high-frequency gain is not known, a new type of switching function is

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... roduced that guarantees switching convergence independent of gain adaptation.