Controllability and reachability of singular linear discrete time   systems
  The main objective of this article is to develop a matrix pencil approach for the study of the controllability and reachability of a class of linear singular discrete time systems. The description equation of a practical system may be established through selection of the proper state variables. Time domain analysis is the method of analyzing the system based on this description equation, through which we may gain a fair understanding of the system's structural features as well as its internal properties. Using time domain analysis, this article studies the fundamentals in system theory such as reachability and controllability. 
Charalambos P. Kontzalis, Grigoris Kalogeropoulos
math.OC cs.SY math.DS