Sakhnovich, L. A. The deficiency indices of a system of first-order differential equations. (English. Russian original) Zbl 0942.34071 Sib. Math. J. 38, No. 6, 1182-1183 (1997); translation from Sib. Mat. Zh. 38, No. 6, 1360-1361 (1997). 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 \(2m \times 2m\), \[ J=\begin{pmatrix} 0 & E_m \\ E_m & 0 \end{pmatrix}. \] Reviewer: N.A.Kudryavtseva (Novosibirsk) Cited in 4 Documents MSC: 34L40 Particular ordinary differential operators (Dirac, one-dimensional Schrödinger, etc.) 34L05 General spectral theory of ordinary differential operators Keywords:Dirac-type system PDFBibTeX XMLCite \textit{L. A. Sakhnovich}, Sib. Math. J. 38, No. 6, 1360--1361 (1997; Zbl 0942.34071); translation from Sib. Mat. Zh. 38, No. 6, 1360--1361 (1997) Full Text: DOI References: [1] L. A. Sakhnovich, ”Problems of factorization and operator identities,” Uspekhi Mat. Nauk,41, No. 1, 3–55 (1986). · Zbl 0613.47017 [2] B. M. Levitan and I. S. Sargsyan, Introduction to Spectral Theory [in Russian], Nauka, Moscow (1970). · Zbl 0225.47019 This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.