We characterize single-item auction formats that are shill-proof in the sense that a profit-maximizing seller has no incentive to submit shill bids. We distinguish between strong shill-proofness, in which a seller with full knowledge of bidders' valuations can never profit from shilling, and weak shill-proofness, which requires only that the expected equilibrium profit from shilling is non-positive. The Dutch auction (with a suitable reserve) is the unique (revenue-)optimal and strongly shill-proof auction. Any deterministic auction can satisfy only two properties in the set {static, strategy-proof, weakly shill-proof}. Our main results extend to settings with affiliated and interdependent values.

翻译：本文系统刻画了单物品拍卖机制中的防伪特性，即追求利润最大化的卖方缺乏提交虚假竞价（马甲竞价）动机的拍卖形式。我们区分了强防伪性与弱防伪性：强防伪性要求即使卖方完全掌握竞标者估值信息，也永远无法通过虚假竞价获利；弱防伪性仅要求虚假竞价的期望均衡利润非正。研究证明，荷兰式拍卖（配合适当保留价）是唯一同时满足（收益）最优性与强防伪性的拍卖机制。任何确定性拍卖机制最多只能同时满足{静态性、策略证明性、弱防伪性}三个属性中的两个。本文主要结论可进一步推广至关联估值与相互依赖估值的场景。