Controllability and observability at infinity of linear time-varying descriptor systems - brief paper

Controllability and observability at infinity of linear time-varying descriptor systems are considered. New characterisations of controllability and observability at infinity are given. Based on the definitions of controllability and observability at infinity, necessary and sufficient conditions for these properties are obtained and presented in terms of original system parameters. The present framework is shown to overcome several difficulties inherent in other treatments of descriptor systems.