Rationality from a computational standpoint

A computationally viable choice function possesses, in addition to other important properties, adaptability - as new alternatives become feasible the set of best alternatives corresponding to the new feasible set can be located without having to reconsider previously rejected alternatives. Adaptability is shown to be closely related to, in fact characteristic of, the standard notions of rationality (expressed in terms of transitivity properties). Adaptability provides a generalization of conventional rationality and in addition leads to the choice function proposed by Schwartz, albeit from an entirely different route, that of computational viability.