… We prove that combinatorial demand functions are characterized by two properties:
continuity and the law of demand. … We prove that combinatorial demand functions are
characterized by two properties: continuity and the law of demand. Assume a finite
collection of items. We are interested in the demand for packages, or bundles of items. For
each vector of item prices, we are given a collection of demanded packages, and we want
to know if there exists a valuation function for packages such that the demanded packages …