Наведено нове доведення інтегрального зображення узагальнених ядер Тепліца, яке базується на спектральній теорії відповідного диференціального оператора, що діє в гільбертовому просторі, побудованому за таким ядром. Одержано теорему про умови на ядро, які забезпечують самоспряженість цього оператора (тобто єдність міри в зображенні).

Індекс рубрикатора НБУВ: В162.1

Рубрики:

Лінійні, лінійні нормовані і лінійні топологічні простори

Шифр НБУВ: Ж26161 Пошук видання у каталогах НБУВ 

Запропоновано узагальнення розширеного стохастичного інтеграла на випадок інтегрування відносно широкого класу випадкових процесів. Зокрема, одержано умови, за яких вказаний інтеграл збігається з класичним стохастичним інтегралом Іто.

Індекс рубрикатора НБУВ: В162.41 + В162.7

Рубрики:

Спектральний аналіз самоспряжених і унітарних операторів

Міри. Інваріантні міри. Динамічні системи. Ергодичні теореми

Шифр НБУВ: Ж26161 Пошук видання у каталогах НБУВ 

Викладено підхід до знаходження розв'язку задачі Коші для вказаного ланцюжка Тоди за допомогою оберненої спектральної задачі.

The article is devoted to a solution of the complex moment problem in the exponential form.

Індекс рубрикатора НБУВ: В161.514.2

Шифр НБУВ: Ж41243 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В161.637

Рубрики:

Ортогональні поліноми

Шифр НБУВ: Ж41243 Пошук видання у каталогах НБУВ 

The classical power moment problem can be viewed as a theory of spectral representations of a positive functional on some classical commutative algebra with involution. We generalize this approach to the case where the algebra is a special commutative algebra of functions on the space of multiple finite configurations. If the above-mentioned functional is generated by a measure on the space of usual finite configurations then this measure is a correlation measure for a probability spectral measure on the space of infinite configurations. The latter measure is practically arbitrary, so that we have a connection between this complicated measure and its correlation measure defined on more simple objects that are finite configurations. The paper gives an answer to the following question: when this latter measure is a correlation measure for a complicated measure on infinite configurations? (Such measures are essential objects of statistical mechanics.)

The solution of the Cauchy problem for differential-difference double-infinite Toda lattice by means of inverse spectral problem for semi-infinite block Jacobi matrix is given. Namely, we construct a simple linear system of three differential equations of first order whose solution gives the spectral matrix measure of the aforementioned Jacobi matrix. The solution of the Cauchy problem for the Toda lattice is given by the procedure of orthogonalization w.r.t. this spectral measure, i.e. by the solution of the inverse spectral problem for this Jacobi matrix.

Індекс рубрикатора НБУВ: В162.4

Рубрики:

Оператори у гільбертовому просторі

Шифр НБУВ: Ж41243 Пошук видання у каталогах НБУВ 

In this article we propose an approach to the strong Hamburger moment problem based on the theory of generalized eigenvectors expansion for a selfadjoint operator. Such an approach to another type of moment problems was given in our works earlier, but for strong Hamburger moment problem it is new. We get a sufficiently complete account of the theory of such a problem, including the spectral theory of block Jacobi - Laurent matrices.

The author earlier in [3, 4, 6, 7] proposed some way of integration the Cauchy problem for semi-infinite Toda lattices using the inverse spectral problem for Jacobi matrices. Such a way for double-infinite Toda lattices is more complicated and was proposed in [9]. This article is devoted to a detailed account of the result [3, 4, 6, 7, 9]. It is necessary to note that in the case of double-infinite lattices we cannot give a general solution of the corresponding linear system of differential equations for spectral matrix. Therefore, in this case the corresponding results can only be understood as a procedure of finding the solution of the Toda lattice.

We propose the power moment approach to investigation of double-infinite Toda lattices, which was contained in author's article [6]. As a result, we give the main theorem from [6] in a more effective form.

The article is devoted to a study of Bogoliubov functionals by using methods of the operator spectral theory being applied to the classical power moment problem. Some results, similar to corresponding ones for the moment problem, where obtained for such functionals. In particular, the following question was studied: under what conditions a sequence of nonlinear functionals is a sequence of Bogoliubov functionals.

It is proved that the Poisson measure is a spectral measure of some family of commuting selfadjoint operators acting on a space constructed from some generalization of the moment problem.

The article is devoted to an exact account of initial results about configurations and measures on them, starting from the concept of a unique topologization of the space of all configurations, including both finite and infinite cases (not as it is made in the classical works).