Party implementation

In this study party implementation concept is introduced. Party implementation is an extension of classical implementation allowing different parties to have group-specific choice rules. Members of a party are assumed to act cooperatively according to a common preference. In this context, a choice rule is said to be party implementable if it is robust to co-operative manipulation. In this thesis some necessity and sufficiency results for party implementation are proven. In particular, it is shown that under some restrictions if the societies choice rule is party implementable, an alternative that is chosen by any group should also be chosen by the society. Conversely, it is shown that if the collective choice can be represented by the union of different groups’ choice, then the social choice rule should be party implementable.