 In practice, one needs to consider if the assumptions of the DM world are likely to apply; nevertheless, the efficiency result is a useful benchmark against which to judge whether any policy violation of production efficiency is justified.Diamond (1982) is one of the first papers which explicitly models the search process involved in making trades and hiring workers, which results in equilibrium unemployment.Diamond has focused much of his professional career on the analysis of U.S. Social Security policy as well as its analogs in other countries, such as China.