Knowledge of individual histories and optimal payment arrangements

This article reviews recent work that generalizes a random matching model of money to permit there to be a mix of transactions: some accomplished through the use of tangible media of exchange and the rest through some form of credit. The generalizations are accomplished by specifying assumptions about common knowledge of individual histories that are intermediate between no common knowledge and complete common knowledge. One of the specifications permits a simple representation of the sense in which more common knowledge is beneficial. The other permits a comparison between using outside money and using inside money as a medium of exchange.