An approximation theory of solutions to operator Riccati equations for H/sup /spl infin// control

We discuss H/sup /spl infin// control problems for the linear system in a Hilbert space X, dx(t)/dt=Ax(t)+Bu(t)+Dv(t), x(O)=x/spl isin/X. We develop an approximation theory for the H/sup /spl infin// disturbance attenuation problem.<
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