Switched systems encompass several subsystems and a switching law that specifies which subsystem is active at any given time instant. An example is the DNA system in a cell. The differences between various cells are due to the fact that only a part of the entire DNA is expressed (i.e., is active). A contrived system, referred to as a gene regulating network, determines which genes should be expressed (i.e., switched form "off" to "on") according to the ever changing internal and external conditions.