Economic theory generally involves choice between real-valued criterion vectors x = (xi, …, xn) ε X, where X is the feasible set of such vectors. For example, in the theory of consumer demand, the criterion xi can be interpreted as the quantity demanded of the ith good. Under certainty, a rational consumer would choose a value of x that would maximize the ordinal utility u(x) subject to x ε X. If a function u(x) does not exist, in the paradigm of Marschak , he is not national, his choices are not consistent, and some of them will be regretted. Even greater focus is placed on the multidimensional nature of the criterion function by the alternative approach suggested by Lancaster . His approach views goods or services as being demanded because they yield want-satisfying characteristics to consumers. In general, a good or service has multiple characteristics, any one of which may be shared by more than one good or service (the traditional consumer model is a special case which views the number of characteristics as equal to the number of goods or services). Further, goods or services in combination may possess characteristics (attributes) different from those pertaining to the items separately.