“…Antoniou et al, 1998), whereas the results were extended for non-regular systems by Karampetakis (2004). The algebraic structure of polynomial matrices was studied by Bernstein (2009), Gantmacher (1959), Gohberg et al (2009), Hayton et al (1988), Kaczorek (2007), Karampetakis and Vologiannidis (2003), Karampetakis et al (2004), Praagman (1991), Zaballa and Tisseur (2012), and in the references cited therein. An interesting problem that we face in this paper is the following inverse problem: Given a certain forward/backward solution space, find a system of algebraic and difference equations with the prescribed solution space.…”