Karabash I. On similarity of differential operators to selfadjoint ones

Українська версія

Thesis for the degree of Candidate of Sciences (CSc)

State registration number

0405U003334

Applicant for

Specialization

  • 01.01.01 - Математичний аналіз

29-06-2005

Specialized Academic Board

К 11.193.02

Essay

Ordinary differential operators with an indefinite weight are considered. A question of similarity to selfadjoint or normal operators is studied. A criterion of similarity is obtained for the operator (sgn x) p(–i d/dx), where p(t) is a real polynomial. A criterion of similarity for the operator w(x) –1 p( i d/dx), where p(t) is real polynomial of odd order and w(x) is a step-function, is given. Similarity conditions in terms of Cauchy integrals and in terms of Weyl functions are given for the operator A = (sgn x)( -d2/dx2+q). For the case of a finite-zone potential the criterion of similarity is obtained.

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