Complete description is given of the linear pointwise degenerate fourth-order delay-differential systems (with constant coefficients) whose active matrix is semisimple and the passive matrix is nonnilpotent. These systems are described with the help of the language of geometrical invariants of certain elements of the semigroup generated by the matrices of the system.
- controlled linear system with time-delay
- degeneration direction
- minimum time of degeneration
- pointwise completeness
- relatively null-controllable system
- system of ordinary delay differential equations