Comments on "Relationships between internal and external stability for infinite-dimensional systems with application to a servo problem" [with reply]

The author takes exception to two statements in the above referred paper (ibid., vol.33, p.1044-52, Nov. 1988). One is that servo systems for infinite-dimensional systems have only been studied in two papers; the commenter points out two more. The other comment regards exponential decay of the error in L/sup 2/ stability. The authors agree with the commenter's point and add some clarification.<
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