Essays in economics. I) Information revelation in market with pairwise meetings. II) Intergenerational fairness

(eng) Many people think that market economy is characterized by decentralized process of prices formation. Moreover, numerous people are convinced that prices convey some information. Few economic frameworks deal those two intuitions. Moreover, this literature uses a game theoretic approach. Therefore and regrettably, the results established vary dramatically according to the assumptions while the modeling differences may appear to be details. This thesis, in its first part, looks for reasons which explain some strong differences among the results of this literature. The credo is that a modeling difference appears to be a detail as long as the underlying mechanism is not understood. Obviously, intergenerational justice is a highly debated topic nowadays. It is the subject of the second part. Two contributions are brought to the literature. The first one proposes to study the issue without comparability of utilities. Economists are reluctant to use utilities comparability. Indeed, it implies value judgments which cannot be founded on scientific arguments. Surprisingly, there is few works in economics which analyzes intergenerational fairness without utilities comparability. This dissertation contributes to fill part of this gap in the theory. The second contribution starts from the concept of sustainable development defined by the Brundtland commission. Several transcriptions of this concept have been proposed in economic models. The goal is to apply one of those transcriptions in a policy making perspective. Indeed, existing works are rather empiric and say little about the optimal trajectory under a sustainability constraint.