Core and Coalitional Fairness: The Case of Information Sharing Rule

We investigate two of the most extensively studied cooperative notions in a pure exchange economy with asymmetric information. One of them is the core and the other is known as coalitional fairness. The set of agents is modelled by a mixed market consisting of some large agents and an ocean of small agents; and the commodity space is an ordered Banach space whose positive cone has an interior point. The information system in our framework is the one introduced by Allen in [1]. Thus, the same agent can have common, private or pooled information when she becomes member of different coalitions. It is shown that the main results in Grodal [20], Schmeidler [26] and Vind [31] can be established when the economy consists of a continuum of small agents. We also focus on the information mechanism based on size of coalitions introduced in [18] and obtain a result similar to the main result in [18]. Finally, we examine the concept of coalitional fairness proposed in [21]. We prove that the core is contained in the set of coalitionally fair allocations under some assumptions. This result provides extensions of Theorem 2 in [21] to an economy with asymmetric information as well as a deterministic economy with infinitely many commodities. Although we consider a general commodity space, all our results were so far unsolved to the case of information sharing rule with finitely many commodities.