Reciprocal Exchange: A Self-Sustaining System
通过形式化模型分析互惠交换（礼物交换）与货币市场交换的互动，解释为何互惠交换在低效时仍能持续，而高效时却可能被市场摧毁。
Reciprocal exchange, or gift exchange, remains a widespread means of obtaining goods and services. This paper examines the persistence of reciprocal exchange by formalizing the interaction between self-enforcing exchange agreements and monetary market exchange. When more people engage in reciprocal exchange, market search costs increase, reciprocity is easier to enforce and yields higher utility. Thus, personalized exchange can persist even when it is inefficient. Conversely, large markets can destroy reciprocity when reciprocal exchange is efficient. The results characterize the use of personal "connections" as a system of reciprocal exchange and explain the disappearance of reciprocity when tribes encounter markets.