Action Is Not Observation: Declaration as the Boundary Event of Action Establishment in Autonomous Systems

Autonomous systems treat producing a physical change and establishing that change as their own action as one event. A command, an actuator fault and an external disturbance leave the same physical result, and observation alone cannot decide whether the result was the system's action. This paper defines declaration as the system-internal boundary event that separates the two facts. A declaration is a discrete, irreversible and non-retroactive internal event marking that the system's physical state has been determined and confirmed admissible as an input to its control computation; it is not the outcome of a judgement, an evaluation or an authorization. The states before a declaration form the pre-action state space, and a change that occurred there is never later promoted to an action by any interpretation. We give the definitions, four properties, what a declaration is not, and its relation to neighbouring concepts. Implementation and evaluation are outside the scope of this paper. Keywords: autonomous systems, action establishment, declaration, pre-action state space, non-retroactivity