Preference Conditions for Invertible Demand Functions
研究了效用最大化消费者的偏好需满足什么条件，才能使需求函数连续且可逆，发现严格凸性、严格单调性和鲁宾斯坦可微性是充要条件，并讨论了与严格需求定律的关系。
It is frequently assumed in several domains of economics that demand functions are invertible in prices. At the primitive level of preferences, however, the corresponding characterization has remained elusive. We identify necessary and sufficient conditions on a utility-maximizing consumer’s preferences for her demand function to be continuous and invertible: strict convexity, strict monotonicity, and differentiability in the sense of Rubinstein (2006). We further show that Rubinstein differentiability is equivalent to the indifference sets being smooth, which is weaker than Debreu’s (1972) notion of preference smoothness. We finally discuss implications of our analysis for demand functions that satisfy the “strict law of demand.”