On the optimality of monetary trading
在一个随机匹配且需求双重巧合缺失的环境中，研究信息处理中心记录交易历史时，货币交易机制是否最优。结论是任何非自给自足的均衡交易机制在总量上等价于货币交易，且最优机制必为货币交易。
Abstract People have long been trading in a “monetary” way. This persistence of monetary trading suggests that it might be an efficient trading mechanism. We formalize this intuition in a random-matching, absence-of-double-coincidence-of-wants environment. The record-keeping technology is operated by an information-processing center which summarizes and updates individuals’ past trading behavior in a binary variable. A trading mechanism consists of an updating rule and an individual trading behavior rule. To capture the difficulties in collecting and processing information about others’ past behavior, we assume that the center faces costs, both fixed and variable, to operate. We show that (1) any non-autarkic equilibrium trading mechanism is, in terms of aggregate variables (such as consumption and frequency of trade), observationally equivalent to a monetary trading mechanism and (2) any non-autarkic optimal equilibrium trading mechanism is a monetary trading mechanism.