Vadim Mogilevskii

  1. Boundary relations and boundary conditions for general (not necessarily definite) canonical systems with possibly unequal deficiency indices.

    Authors: Vadim Mogilevskii
    Subjects: Functional Analysis
    Abstract

    We investigate in the paper general (not necessarily definite) canonical
    systems of differential equation in the framework of extension theory of
    symmetric linear relations. For this aim we first introduce the new notion of a
    boundary relation $\G:\gH^2\to\HH$ for $A^*$, where $\gH$ is a Hilbert space,
    $A$ is a symmetric linear relation in $\gH, \cH_0$ is a boundary Hilbert space
    and $\cH_1$ is a subspace in $\cH_0$.

  2. Minimal spectral functions of an ordinary differential operator.

    Authors: Vadim Mogilevskii
    Subjects: Functional Analysis
    Abstract

    Let $l[y]$ be a formally selfadjoint differential expression of an even order
    on the interval $[0,b> \;(b\leq \infty)$ and let $L_0$ be the corresponding
    minimal operator. By using the concept of a decomposing boundary triplet we
    consider the boundary problem formed by the equation $l[y]-\l y=f\;(f\in
    L_2[0,b>)$ and the Nevanlinna $\l$-depending boundary conditions with constant
    values at the regular endpoint 0.

  3. On generalized resolvents and characteristic matrices of differential operators.

    Authors: Vadim Mogilevskii
    Subjects: Functional Analysis
    Abstract

    The main objects of our considerations are differential operators generated
    by a formally selfadjoint differential expression of an even order on the
    interval $[0,b> (b\leq \infty)$ with operator valued coefficients. We
    complement and develop the known Shtraus' results on generalized resolvents and
    characteristic matrices of the minimal operator $L_0$.

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