We consider the problem of funding public goods that are complementary in nature. Examples include charities handling different needs (e.g., protecting animals vs. providing healthcare), charitable donations to different individuals, or municipal units handling different issues (e.g., security vs. transportation). We model these complementarities by assuming Leontief preferences; that is, each donor seeks to maximize an individually weighted minimum of all contributions across the charities. Decentralized funding may be inefficient due to a lack of coordination among the donors; centralized funding may be undesirable as it ignores the preferences of individual donors. We present a mechanism that combines the advantages of both methods. The mechanism efficiently distributes each donor's contribution so that no subset of donors has an incentive to redistribute their donations. Moreover, it is group-strategyproof, satisfies desirable monotonicity properties, maximizes Nash welfare, returns a unique Lindahl equilibrium, and can be implemented via natural best-response spending dynamics.

翻译：本研究探讨具有互补性的公共物品融资问题。此类场景包括：处理不同需求的慈善机构（例如动物保护与医疗救助）、针对不同个体的慈善捐赠，或处理不同事务的市政单位（例如治安与交通）。我们通过假设Leontief偏好来建模这种互补性：每位捐赠者旨在最大化所有慈善机构受赠金额的个体加权最小值。由于捐赠者间缺乏协调，分散式融资可能导致效率低下；而集中式融资因忽视个体偏好亦非理想方案。本文提出一种融合两种方法优势的机制。该机制能高效分配每位捐赠者的贡献，使得任意捐赠者子集均无重新分配捐赠的动机。此外，该机制具有群组防策略性，满足理想的单调性条件，可实现纳什福利最大化，返回唯一的林达尔均衡，并能通过自然的最佳响应支出动态予以实施。