Trigger-Target Rules Need Not be Optimal with Fixed Adjustment Costs: A Simple Comment on Optimal Money Holding Under Uncertainty
用一个简单例子说明，在离散时间货币需求模型中，最优货币规则可能比文献中假设的简单触发目标规则复杂得多；但在连续时间模型或单向调整时，简单规则仍最优。
Literature concerning the transactions theory of demand for money often contains the assumption that simple trigger-target rules are optimal when each financial transaction is accompanied by a fixed cost. The validity of this assumption is examined in this paper. Using a simple example, it is shown that the optimal money rule in discrete time models of money demand may be much more complicated than the simple rules assumed to be optimal in the literature. However, when considering continuous time models of money demand or when adjustment of the money stock is allowed in one direction only, simple trigger-target rules are in fact optimal. Copyright 1990 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.