A Borg-type Theorem Associated with Orthogonal Polynomials on the Unit Circle Fritz Gesztesy and Maxim Zinchenko
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چکیده
We prove a general Borg-type result for reflectionless unitary CMV operators U associated with orthogonal polynomials on the unit circle. The spectrum of U is assumed to be a connected arc on the unit circle. This extends a recent result of Simon in connection with a periodic CMV operator with spectrum the whole unit circle. In the course of deriving the Borg-type result we also use exponential Herglotz representations of Caratheodory functions to prove an infinite sequence of trace formulas connected with the CMV operator U .
منابع مشابه
Weyl–titchmarsh Theory for Cmv Operators Associated with Orthogonal Polynomials on the Unit Circle Fritz Gesztesy and Maxim Zinchenko
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