In economics, a unit demand agent is an agent who wants to buy a single item, which may be of one of different types.
A typical example is a buyer who needs a new car.
There are many different types of cars, but usually a buyer will choose only one of them, based on the quality and the price.
If there are m different item-types, then a unit-demand valuation function is typically represented by m values
representing the subjective value that the agent derives from item
If the agent receives a set
A unit-demand valuation is formally defined by: A unit-demand function is an extreme case of a submodular set function.
It is characteristic of items that are pure substitute goods.