• Since W(s) has no jw-axis zeros, we conclude that ||G||¥ < g .
• (vi) Û (vii): follows
from Schur complement.
• (vi) Þ (i): by following
the similar procedure as above.
• (i) Þ (vi): let
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•
• Then
there exists an e>0 such that ||Ge||¥ < g . Now (vi) follows by applying part (v) to Ge .
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