Three years ago, very few economists would have imagined that one of the newest and fastest growing research areas in international trade is the use of quantitative trade models to estimate the economic welfare losses from dissolutions of major countries' economic integration agreements (EIAs)....

Should a subset of member states of a federation be allowed to form a sub-union on some policy issue? When centralization is not politically feasible, allowing an enhanced cooperation agreement among a subset of countries permits the latter to gain benefits which would otherwise be lost....