Revealed Preference in a Discrete Consumption Space
证明在离散消费空间中，只要消费者满足成本效率，其行为就服从广义显示偏好公理（GARP），并可通过Afriat定理找到严格递增的效用函数来合理化价格与需求数据。
We show that an agent maximizing some utility function on a discrete (as opposed to continuous) consumption space will obey the generalized axiom of revealed preference (GARP), so long as the agent obeys cost efficiency. Cost efficiency will hold if there is some good, outside the set of goods being studied by the modeler, that can be consumed by the agent in continuous quantities. An application of Afriat's Theorem then guarantees that there is a strictly increasing utility function on the discrete consumption space that rationalizes price and demand observations.