We examine the possibilities of extending Sen's taxonomy of fixed-population information assumptions regarding the measurability and interpersonal comparability of individual utilities to social-choice problems where the population may very.

The rationalizability of a choice function by means of a transitive relation has been analyzed thoroughly in the literature. However, not much seems to be known when transitivity is weakened to quasi-transitivity or acyclicity. We describe the logical relationship between the different notions...

In this paper we will describe a class of three-person games and draw general conclusions about non-cooperative behavior in them.

We provide a characterization of selection correspondences in two-person exchange economies that can be core rationalized in the sens that there exists a preference profil with some standard properties that generates the observed choices as the set core elements of the economy for any given...

The notion of diversity is an issue that is of relevance in several contexts. This paper provides an axiomatic approach to the measurement of diversity. We characterize two nested classes of ordinal measures of diversity and an important member of these classes.

We provide a survey of the literature on ranking sets of objects. The interpretations of those set ranking include those employed in the theory of choice under complete uncertianty, rankings of opportunity sets, set rankings that appear in matching theory, and the structure of assemly proferences.