Abstract
In this work, firstly based on the M.I.Vishik’s results and using methods
of operator theory all solvable extensions of a minimal operator
generated by linear delay differential-operator expression of first order
in the Hilbert space of vector-functions in finite interval are described.
Later on, sharp formulas for the spectrums of these solvable extensions
have been found. Finally, the obtained results has been supported by
applications.