Reachability properties of continuous-time positive systems

In this technical note, reachability properties of continuous-time positive systems are introduced and characterized. Specifically, first it is shown that reachability and strong reachability are equivalent properties, and thus the characterization of strong reachability derived in [8] is extended to the weaker notion of reachability. In the second part of the technical note, essential reachability is introduced, and necessary and sufficient conditions for this property to hold are provided. Index Terms--Continuous-time positive system, directed graph, essential reachability, reachability, strong reachability.