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Characterizations of Strategy-Proof Mechanisms for Excludable versus Nonexcludable Public Projects

First, we characterize “the unanimous mechanisms” as the set of strategy-proof, individually rational, and citizen sovereign mechanisms for the provision of a nonexcludable public project. Second, we characterize “the largest unanimous mechanisms” as the set of strategy-proof, individually rational, demand-monotonic, and access-independent mechanisms for the provision of an excludable public project. Comparing these two classes of mechanisms, we conclude that admitting partial exclusion always improves efficiency under the incentive compatibility constraint. Journal of Economic Literature Classification Numbers: D71, D82, H41.