Constructive expressive power of population protocols

Abstract: Population protocols are a model of distributed computation intended for the study of networks of independent computing agents with dynamic communication structure. Each agent has a finite number of states, and communication opportunities occur nondeterministically, allowing the agents involved to change their states based on each other's states. Population protocols are often studied in terms of reaching a consensus on whether the input configuration satisfied some predicate. In the present paper we propose an alternative point of view. Instead of studying the properties of inputs that a protocol can recognise, we study the properties of outputs that a protocol eventually ensures. We define constructive expressive power. We show that for general population protocols and immediate observation population protocols the constructive expressive power coincides with the normal expressive power. Immediate observation protocols also preserve their relatively low verification complexity in the constructive expressive power setting.