대한수학회논문집 (Communications of the Korean Mathematical Society)
- 제13권4호
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- Pages.801-810
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- 1998
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- 1225-1763(pISSN)
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- 2234-3024(eISSN)
FACTORIZATION IN KREIN SPACES
초록
Let A(z), W(z) and C(z) be power series with operator coefficients such that W(z) = A(z)C(z). Let D(A) and D(C) be the state spaces of unitary linear systems whose transfer functions are A(z) and C(z) respectively. Then there exists a Krein space D which is the state space of unitary linear system with transfer function W(z). And the element of D is of the form (f(z) + A(z)h(z), k(z) + C*(z)g(z)) where (f(z),g(z)) is in D(A) and (h(z),k(z)) is in D(C).