9 citations · 19 across the 16 of their papers we have counts for
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Spectral Theory of Dirac Operators
Tigran Harutyunyan, Yuri Ashrafyan
The main issues of the spectral theory of Dirac operators are presented, namely: transformation operators, asymptotics of eigenvalues and eigenfunctions, description of symmetric a…
On Ambarzumyan-type Inverse Problems of Vibrating String Equations
Yuri Ashrafyan, Dominik L. Michels
We consider the inverse spectral theory of vibrating string equations. In this regard, first eigenvalue Ambarzumyan-type uniqueness theorems are stated and proved subject to separa…
Inverse Sturm-Liouville problems with summable potential
Yuri Ashrafyan, Tigran Harutyunyan
We describe the necessary and sufficient conditions for two sequences {μ_n}^\infty_n=0 and {a_n}^\infty_n=0 to be correspondingly the set of eigenvalues and the set of norming cons…
A new kind of uniqueness theorems for inverse Sturm-Liouville problems
Yuri Ashrafyan
We prove Marchenko-type uniqueness theorems for inverse Sturm-Liouville problems. Moreover, we prove a generalization of Ambarzumyans theorem.
On a property of norming constants of Sturm-Liouville problem
Yuri Ashrafyan, Tigran Harutunyan
A connection, which shows the dependence of norming constants on boundary conditions, was found using the Gelfand-Levitan method for the solution of inverse Sturm-Liouville problem…
Isospectral Dirac operators
Yuri Ashrafyan, Tigran Harutyunyan
We give the description of self-adjoint regular Dirac operators, on , with the same spectra.
Dirac operator with linear potential and its perturbations
Yuri A. Ashrafyan, Tigran N. Harutyunyan
We prove that canonical Dirac expression with linear potential generates operators on axis and half axis, for which we can find the eigenvalues and eigenfunctions in explicit form.…
Inverse Sturm-Liouville problems with fixed boundary conditions
Tigran Harutyunyan, Yuri Ashrafyan
Necessary and sufficient conditions for two sequences and to be the spectral data for a certain Sturm-Liouville problem are well know…
On the "movement" of the zeros of eigenfunctions of the Sturm-Liouville problem
Tigran Harutyunyan, Avetik Pahlevanyan, Yuri Ashrafyan
We study the dependence of the zeros of eigenfunctions of Sturm-Liouville problem on the parameters that define the boundary conditions. As a corollary, we obtain Sturm oscillation…