 A considerable part of rational choice theory is concerned with formalizations of conditions of rationality and investigation of their implications. When an agent’s preferences are complete and transitive and satisfy a further continuity condition, then they can be represented by a so-called ordinal utility function. What this means is that it is possible to define a function that represents an agent’s preferences so that U(X) &gt; U(Y) if and only if the agent prefers X to Y, and U(X) = U(Y) if and only if the agent is indifferent between X and Y. This function merely represents the preference ranking. It contains no information beyond the ranking. Any order-preserving transformation of “U” would represent the agent’s preferences just as well.