Spectral Order and Isotonic Differential Operators of Laguerre-pólya Type
نویسنده
چکیده
Abstract. The spectral order on Rn induces a natural partial ordering on the manifold Hn of monic hyperbolic polynomials of degree n. We show that all differential operators of Laguerre-Pólya type preserve the spectral order. We also establish a global monotony property for infinite families of deformations of these operators parametrized by the space l of real bounded sequences. As a consequence, we deduce that the monoid A of linear operators that preserve averages of zero sets and hyperbolicity consists only of differential operators of Laguerre-Pólya type which are both extensive and isotonic. In particular, these results imply that any hyperbolic polynomial is the global minimum of its A-orbit and that Appell polynomials are characterized by a global minimum property with respect to the spectral order.
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تاریخ انتشار 2004