On the structure of choice under different external references

In this paper we fully characterize an individual's choice behaviour according to three different so-called external references. The first system which we describe axiomatically is standard utility maximization or preference optimization. The second approach characterizes the choice of the second largest element as an optimal choice, the third system is the choice of a medium element, also as a first best choice. For all three approaches, we have established a common axiomatic structure which allows us to point out rather precisely congruences and divergences among the different systems considered.