Lexicographic Orderings

Lexicographic orderings are orderings in which certain elements of the space being ordered have been selected for special treatment. I begin with an example. Suppose an agent has an ordering over commodities a and b. Although he or she likes both a and b, any bundle which has more of a is preferred to any bundle which has less of a. Of course among bundles which have the same amount of a, bundles with more b are preferred to those with less. Thus, there are no trade-offs between a and b and each indifference set is a single point. The name ‘lexicographic’ comes from the way words are ordered in a dictionary, alphabetically by the first letter and then the second and so on.