Information disclosure with many alternatives

We consider two-stage collective decision problems where some agents have private information about alternatives and others don’t. In the first stage informed (experts) may or not disclose their information, thus eventually influencing preferences of those initially uninformed. second resulting all after disclosure are aggregated by a social choice function. provide general conditions on functions guaranteeing that outcome will be same would obtain if shared available in society. Experts should granted coalitional veto power: changes due to other harm experts at time. then specialize our results. When set is priori determined, we characterize strategy-proof rules defined single-peaked separable preference domains ensure desired level disclosure. also prove that, when unknown, no voting rule can fully achieve this goal, but majority provides unique best solution profiles single-peaked.