Cooperation and Competition when Bidding for Complex Projects: Centralized and Decentralized Perspectives

To successfully complete a complex project, be it a construction of an airport or of a backbone IT system, agents (companies or individuals) must form a team having required competences and resources. A team can be formed either by the project issuer based on individual agents' offers (centralized formation); or by the agents themselves (decentralized formation) bidding for a project as a consortium---in that case many feasible teams compete for the contract. We investigate rational strategies of the agents (what salary should they ask? with whom should they team up?). We propose concepts to characterize the stability of the winning teams and study their computational complexity

A Theory of coalition Bargaining

When voting takes place in democratic institutions, we find (either explicitly or implicitly) that there is an agenda setter or a formateur. Such players are uniquely able to make substantive proposals for given topics. Their statuses remain intact even after rejection of proposals, but they must revise rejected proposals constructively (e.g. towards a compromise). We model this in a general environment, show that the equilibrium outcome is generically unique, and characterize it explicitely. The equilibrium outcome is robust to (partially) binding communication between the formateur and the voters. As illustrations, we consider majority bargaining about a cake (leaned on Baron and Ferejohn,1989),where the formateur ends up being a perfect dictator, and a model of legislative voting (leaned on Jackson and Moselle,2002), where he is a dictator if his ideological position is within the quartiles of the parliament. In these cases, our model implements (reversed) McKelvey majority path. Depending on the valuations, the formateur´s power may be weakened when parliamentary decisions can be revised, as this may faciliate tacit collusion amongst the voters. --coalitional bargaining,legislature,non-cooperative

Aspiration Dynamics of Multi-player Games in Finite Populations

Studying strategy update rules in the framework of evolutionary game theory, one can differentiate between imitation processes and aspiration-driven dynamics. In the former case, individuals imitate the strategy of a more successful peer. In the latter case, individuals adjust their strategies based on a comparison of their payoffs from the evolutionary game to a value they aspire, called the level of aspiration. Unlike imitation processes of pairwise comparison, aspiration-driven updates do not require additional information about the strategic environment and can thus be interpreted as being more spontaneous. Recent work has mainly focused on understanding how aspiration dynamics alter the evolutionary outcome in structured populations. However, the baseline case for understanding strategy selection is the well-mixed population case, which is still lacking sufficient understanding. We explore how aspiration-driven strategy-update dynamics under imperfect rationality influence the average abundance of a strategy in multi-player evolutionary games with two strategies. We analytically derive a condition under which a strategy is more abundant than the other in the weak selection limiting case. This approach has a long standing history in evolutionary game and is mostly applied for its mathematical approachability. Hence, we also explore strong selection numerically, which shows that our weak selection condition is a robust predictor of the average abundance of a strategy. The condition turns out to differ from that of a wide class of imitation dynamics, as long as the game is not dyadic. Therefore a strategy favored under imitation dynamics can be disfavored under aspiration dynamics. This does not require any population structure thus highlights the intrinsic difference between imitation and aspiration dynamics