Dindar, HayrullahLaffond, GilbertLaine, Jean2024-07-182024-07-182015978-3-319-19515-5978-3-319-19514-81865-1348https://doi.org/10.1007/978-3-319-19515-5_18https://hdl.handle.net/11411/697815th International Conference on Group decision and negotiation (GDN) -- JUN 22-26, 2015 -- Warsaw, POLANDWe investigate group manipulation by vote exchange in two-tiers elections, where voters are first distributed into districts, each with one delegate. Delegates' preferences result from aggregating voters' preferences district-wise by means of some aggregation rule. Final outcomes are sets of alternatives obtained by applying a social choice function to delegate profiles. An aggregation rule together with a social choice function define a constitution. Voters' preferences over alternatives are extended to partial orders over sets by means of either the Kelly or the Fishburn extension rule. A constitution is Kelly (resp. Fishburn) swapping-proof if no group of voters can get by exchanging their preferences a jointly preferred outcome according to the Kelly (resp. Fishburn) extension. We establish sufficient conditions for swapping-proofness. We characterize Kelly and Fishburn swapping-proofness for Condorcet constitutions, where both the aggregation rule and the social choice function are based on simple majority voting. JEL Class D71, C70.eninfo:eu-repo/semantics/closedAccessRepresentative DemocracyVote SwappingVote ExchangeGroup ManipulationManipulationConference Object2-s2.0-8493740968310.1007/978-3-319-19515-5_18239Q2227218N/AWOS:000365186900028