Abstract:
In ordering in_nite utility streams, anonymity and Pareto are considered two basic principles. Anonymity is usually expressed by means of a group of cyclic or Pareto-compatible permutations. Maximal (for inclusion) groups of cyclic permutations involve free ultra_lters on the lattice of partitions of positive integers and are therefore nonconstructible objects. This result is in line with the conjecture of Fleurbaey and Michel (2003) and with the results of Lauwers (2006) and Zame (2007).