A Note on Portfolio Dominance
指出Landsberger和Meilijson（1993）提出的条件对于投资组合占优是必要但不充分的，并给出了精确的充要条件，对研究风险资产需求的经济学者有参考价值。
In the standard portfolio problem, a shift in the distribution of the risky asset is "portfolio-dominated" if it reduces the demand for the risky asset by all risk-averse agents, irrespective of the risk-free rate. We show that the condition obtained by Landsberger and Meilijson (1993), while necessary, is not sufficient for portfolio dominance and we present an exact necessary and sufficient condition.