“…For discrete-time descriptor systems, the state estimation is presented recursively and the resulting generalized Kalman filter has been intensively studied (see e.g. (Dai, 1989), (Darouach et al, 1993), (Deng and Liu, 1999), (Ishihara et al, July 2004a), (Keller et al, 1992), (Nikoukhah et al, 1999), (Nikoukhah et al, 1992), (Zhang et al, 1999), (Zhang et al, 1996)). Different formulations have been proposed in order to deal with this problem.…”