Inverse problem for Dirac operators with two constant delays (Q6554755)

Authors study inverse spectral problems for Dirac-type functional-differential operators with two constant delays greater than two fifths the length of the interval, under Dirichlet boundary conditions. The inverse problem of recovering operators from four spectra has been studied. They consider cases when delays are greater or less than half the length of the interval. The main result of the paper refers to the proof that in both cases operators can be recovered uniquely from four spectra. The paper [\textit{S. Buterin} and \textit{N. Djurić}, Lobachevskii J. Math. 43, No. 6, 1492--1501 (2022; Zbl 1507.34083)]] dealing with Dirac operators with one constant delay greater than half the length of the interval, is the first result in this direction. In this paper authors reconstructed a unique solution of BVPs from either two complete spectra or two subspectra of BVPs. This result obtained in this work can be regarded as a better and complete reconstruction algorithm for this inverse spectral problem.