The deficiency indices of a system of first-order differential equations (Q1972651)

The theorem by B. M. Levitan on the deficiency indices of Dirac-type systems is extended to systems of the form \[ \frac{dw}{dx} = i z J H (x) w, \qquad 0 \leq x \leq \infty. \] Here, \(H(x)\geq 0\) is a locally summable matrix-valued function of order \(2m \times 2m\), \[ J=\begin{pmatrix} 0 & E_m \\ E_m & 0 \end{pmatrix}. \]