Combinatorial Civic Crowdfunding with Budgeted Agents: Welfare Optimality at Equilibrium and Optimal Deviation

Civic Crowdfunding (CC) uses the ``power of crowd" to garner contributions towards public projects. As these projects are non-excludable, agents may prefer ``free-ride," resulting in project not being funded. Researchers introduce refunds for single CC incentivize contribute, guaranteeing project's funding. These funding guarantees applicable only when have an unlimited budget. This paper focuses on a combinatorial setting, where multiple available and limited We study specific conditions can be guaranteed. Naturally, optimal social welfare subset is desirable every cannot funded due budget restrictions. prove impossibility achieving at equilibrium any monotone refund scheme. Further, given other agents, we that it NP-Hard agent determine its strategy. That is, while profitable deviations exist instead subset, computationally hard find deviation. Consequently, different heuristics use contribute practice. demonstrate heuristics' performance as average-case trade-off between obtained agent's utility through simulations.