Resumen de Rational expectation can preclude trades

Takashi Matsuhisa, Ryuichiro Ishikawa

• In a pure exchange economy under uncertainty the traders are willing to trade of the amounts of state-contingent commodities and they know their expectations.

  Common-knowledge about these conditions among all traders can preclude trade if the initial endowments allocation is a rational expectations equilibrium, even when the traders have the non-partition structure of information without the common prior assumption. In the proof it plays essential role to extend the notion of a rational expectations equilibrium and to characterize ex-ante Pareto optimal endowments as the equilibrium. From the epistemic point of view it is emphasized that the partition structure of information for the traders plays no roles in the no trade theorem.