Participative methods and consensus theory

The present Technical Report contains a concise analysis of some participatory methods and a discussion of the method of consensus as a formal tool for decisionmaking.
The treatment is kept at an informal and colloquial level with the aim to be precise and concise.
Thei Technical Report relies mainly on classical results, so that it may be considered as a real primer on these topics, but contains also novel materials and results.
Reports of errors and inaccuracies are greatefully appreciated.