منابع مشابه
Products of Positive Operators
A number of mathematicians have considered the problem of writing an operator as a product of \nice" operators, such as positive, hermitian or normal operators. Our principal reference for this is a paper of P.Y. Wu 6], but see also 2] and 5]. This kind of question, and related questions, have also been considered in a C*-algebra context, see 3]. A core result of Wu's paper is his theorem that ...
متن کاملPositive Perturbations of Unbounded Operators
This work studies the spectral properties of certain unbounded selfadjoint operators by considering positive perturbations of such operators and the unitary equivalence of the perturbed and unperturbed transformations. Conditions are obtained on the unitary operators implementing this equivalence which guarantee that the selfadjoint operators have an absolutely continuous part.
متن کاملPositive Decompositions of Exponential Operators
The solution of many physical evolution equations can be expressed as an exponential of two or more operators. Approximate solutions can be systematically derived by decomposing the exponential in a product form. For time-reversible equations, such as the Hamilton or the Schrödinger equation, it is immaterial whether the decomposition coefficients are positive or negative. For timeirreversible ...
متن کاملStructure of positive decompositions of exponential operators.
The solution of many physical evolution equations can be expressed as an exponential of two or more operators acting on initial data. Accurate solutions can be systematically derived by decomposing the exponential in a product form. For time-reversible equations, such as the Hamilton or the Schrödinger equation, it is immaterial whether or not the decomposition coefficients are positive. In fac...
متن کاملTranslation-invariant bilinear operators with positive kernels
We study L (or Lr,∞) boundedness for bilinear translation-invariant operators with nonnegative kernels acting on functions on R. We prove that if such operators are bounded on some products of Lebesgue spaces, then their kernels must necessarily be integrable functions on R, while via a counterexample we show that the converse statement is not valid. We provide certain necessary and some suffic...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Indiana University Mathematics Journal
سال: 1959
ISSN: 0022-2518
DOI: 10.1512/iumj.1959.8.58058