We thank Bettina Klaus, an Associate Editor and a referee for helpful comments. We are specially grateful to William Thomson for his many comments and suggestions. The work of G. Bergantiños is partially supported by research grant ECO2008-03484-C02-01 from the Spanish Ministry of Science and Innovation and FEDER. Support for the research of J. Massó was received through the prize ICREA Acadèmia for excellence in research, funded by the Generalitat de Catalunya. He also acknowledges the support of MOVE, where he is an affiliated researcher, and the Barcelona Graduate School of Economics (through its Research Recognition Programme), where he is an a¢ liated professor. His work is also supported by the Spanish Ministry of Science and Innovation, through grants ECO2008-04756 (Grupo Consolidado-C) and CONSOLIDER-INGENIO 2010 (CDS2006-00016), and by the Generalitat de Catalunya, through grant SGR2009-419. The work of A. Neme is partially supported by the Universidad Nacional de San Luis, through grant 319502, and by the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), through grant PIP 112-200801-00655.

Altres ajuts: CONICET/PIP112-200801-00655

The division problem consists of allocating a given amount of an homogeneous and perfectly divisible good among a group of agents with single-peaked preferences on the set of their potential shares. A rule proposes a vector of shares for each division problem. The literature has implicitly assumed that agents will find acceptable any share they are assigned to. In this paper we consider the division problem when agents participation is voluntary. Each agent has an idiosyncratic interval of acceptable shares where his preferences are single-peaked. A rule has to propose to each agent either to not participate or an acceptable share because otherwise he would opt out and this would require to reassign some of the remaining agents shares. We study a subclass of e¢ cient and consistent rules and characterize extensions of the uniform rule that deal explicitly with agents voluntary participation.