A Game Perspective of Refinement of Component Models

Previous works on formal development for component-based systems usually equate refinement relations as behaviors containment. This setting facilitates verifying safety properties, but can´t capture the intuition that a refined component should more easily react to the environment and is not convenient from a point view of design. To address this issue, we argue in favor of defining refinement of component models in terms of alternating simulation, which is a relation on game models with a game-theoretical interpretation. We investigate the refinement relations of component models in the framework of rCOS, which is a formal development method for component systems. We propose the refinement relations of rCOS contract models and specification models respectively and further prove they are alternating simulations. Finally, we define the composition operator on specifications and show the alternating refinement is compositional with respect to this operator.