- 1. Population protocols
- Introduction
- A formal model
- Stable computation
- Computational complexity
- Overview of the content
- Organization of the text
- Exercises.

- 2. The computational power of population protocols
- Semilinear sets and Presburger arithmetic
- Semilinear predicates are stably computable
- Stably computable predicates are semilinear
- Exercises.

- 3. Enhancing the model
- Introduction
- Composition of protocols: stabilizing inputs
- Probabilistic population protocols
- Epidemics
- 3-state approximate majority protocol
- Virtual register machine simulation
- Community protocols
- The model
- Computational power
- Exercises.

- 4. Mediated population protocols and symmetry
- Symmetric nondeterministic space (n2)
- Stable computation
- Predicates on input assignments
- Stably decidable network properties
- Weakly connected graphs
- Graphs not even weakly connected
- Exercises.

- 5. Passively mobile machines that use restricted space
- The model and the power of log space
- A first inclusion for PMSPACE (log n)
- Assigning unique ids by reinitiating computation
- A better inclusion for PMSPACE (log n)
- An exact characterization for PMSPACE (log n)
- Below log space, above log space and a space hierarchy
- Behavior of the PM model for space o(log log n)
- The logarithmic predicate
- Exercises.

- 6. Conclusions and open research directions
- Conclusions
- Open research directions
- Bibliography
- Acronyms
- Authors' biographies.

Wireless sensor networks are about to be part of everyday life. Homes and workplaces capable of self-controlling and adapting air-conditioning for different temperature and humidity levels, sleepless forests ready to detect and react in case of a fire, vehicles able to avoid sudden obstacles or possibly able to self-organize routes to avoid congestion, and so on, will probably be commonplace in the very near future. Mobility plays a central role in such systems and so does passive mobility, that is, mobility of the network stemming from the environment itself. The population protocol model was an intellectual invention aiming to describe such systems in a minimalistic and analysis-friendly way. Having as a starting-point the inherent limitations but also the fundamental establishments of the population protocol model, we try in this monograph to present some realistic and practical enhancements that give birth to some new and surprisingly powerful (for these kind of systems) computational models.