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A first-order boundary value problem with boundary condition on a countable set of points
A. M. Minkin Saratov State University named after N. G. Chernyshevsky
Abstract:
Let $E=\{E_n\}$ be the family of subspaces spanning the eigenfunctions and adjoint functions of the boundary-value problem
$$
-i\frac{dy}{dx}=\lambda y,\quad -a\le x\le a,\qquad
U(y)\equiv\int_{-a}^ay(t)d\sigma(t)=0,
$$
that correspond to “close” eigenvalues (in the sense of the distance defined as the maximal of the Euclidean and the hyperbolic metrics). For a purely discrete measure $d\sigma$ it is shown that the system $E$ does not form an unconditional basis of subspaces in $L^2(-a,a)$ if at least one of the end points $\pm a$ is mass-free.
Received: 07.07.1995 Revised: 05.12.1996
Citation:
A. M. Minkin, “A first-order boundary value problem with boundary condition on a countable set of points”, Mat. Zametki, 62:3 (1997), 418–424; Math. Notes, 62:3 (1997), 350–355
Linking options:
https://www.mathnet.ru/eng/mzm1623https://doi.org/10.4213/mzm1623 https://www.mathnet.ru/eng/mzm/v62/i3/p418
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Abstract page: | 402 | Full-text PDF : | 179 | References: | 58 | First page: | 2 |
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