  Symbolic control is an abstraction-based controller synthesis approach that
provides, algorithmically, certifiable-by-construction controllers for
cyber-physical systems. Symbolic control approaches usually assume that
full-state information is available which is not suitable for many real-world
applications with partially-observable states or output information. This
article introduces a framework for output-feedback symbolic control. We propose
relations between original systems and their symbolic models based on outputs.
They enable designing symbolic controllers and refining them to enforce complex
requirements on original systems. We provide example methodologies to
synthesize and refine output-feedback symbolic controllers.
