Moneyspots: Extraneous Attributes and the Coexistence of Money and Interest-Bearing Nominal Bonds
证明，如果作为法定货币的实物在某个无关属性上存在异质性，那么货币与有息债券可以共存，解决了回报率占优之谜。
It is folklore among monetary theorists that, under laissez faire, without ad hoc assumptions that favor money over bonds, there do not exist equilibria in which government-issued fiat money coexists with nominal default-free, interest-bearing government bonds with similar physical characteristics. This proposition is the basis for the strongest version of the rate-of-return-dominance puzzle. In this paper I show that if--as has been the case throughout monetary history--the physical object used as fiat money is heterogeneous in an extraneous attribute, then there exist equilibria in which money coexists with interest-bearing bonds.