Consider , , , , , and .
There exists such that
-
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(1)
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if and only if
-
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(2)
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Any matrix satisfying
+ is a solution to (1)
Consider , , , ,, and .
There exists such that
-
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(3)
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if and only if
-
, and
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(4)
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If two inequalities in (4) hold, then a solution to (3) is given by
Consider , , , and , where .
There exists such that
-
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(5)
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if and only if
-
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(6)
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Consider , , , and , where .
-
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(7)
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implies
Consider , , , , , , and
LMI gives
-
, and
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(8)
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if and only if
-
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(9)
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Consider , , , , , , and .
LMI gives
-
, and
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(10)
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are satisfied if and only if
-
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(11)
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Consider , , , , and , , where , , , and .
There exists , , , and such that
-
, and =
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(12)
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if and only if
-
Necessity ((3) (4)) comes from the requirement that the submatrices corresponding to the principle minors of (3) are negative definite
Sufficiency ((4) (3)) is shown by rewriting the matrix inequalities of (4) in the equivalent form
, and
Concatenating the two matrices and choosing gives the equivalent matrix inequality
-
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(3-1)
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or
-
which is equivalent to (3) using the Schur complement lemma.
the LMI in (5) can be written using the Schur complement lemma as
-
-
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(5-2)
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-
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(5-3)
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Using the Schur complement lemma on (7) for
Using the property or equivalent gives