The observability problem of switched linear singular（SLS） systems is studied in this paper. Based on the observability definition, the unobservable subspaces of given switching laws are investigated under the condition that all subsystems are regular. A necessary condition and a sufficient condition for observability of SLS systems are given. It is shown that the observability and controllability are dual for some special SLS systems with circulatory switching laws. The method developed here is applicable to the observability analysis of normal switched linear systems.
＜正＞ This paper addresses the design problem of practical （or satisfaction） output-feedback controls for stocha...
Liu Yun-Gang Zhang Ji-Feng(School of Control Science and Engineering, Shandong University, Jinan, 250061) (Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, 100080)
Consider the second-order semi-linear neutral difference equation △[αn｜△（xn＋pnxn-τ）｜^α-1△（xn＋pnxn-τ）]＋∑i=1^k qi（n）｜xn-σi｜^α-σi=0,（1）The sufficient conditions are established for oscillation of the solutions of （1）. These results generalize and improve some known results about both neutral and delay difference equation.
