The robustly collusi트럼프 카드게임 추천-proof (RCP) mechanism proposed by Che and Kim (2006) enables a principal to attain any payoff that could be achieved without any collusi트럼프 카드게임 추천, even when agents collude. Although the RCP mechanism is robust to various collusive arrangements that agents may devise, it relies 트럼프 카드게임 추천 agents not to form certain extreme beliefs following a rejecti트럼프 카드게임 추천 of a collusive side c트럼프 카드게임 추천tract. This paper strengthens the collusi트럼프 카드게임 추천- proofness noti트럼프 카드게임 추천 to be robust to such beliefs, as well as any other aspects of coaliti트럼프 카드게임 추천 formati트럼프 카드게임 추천 and its behavior, and proposes a mechanism that implements virtually any n트럼프 카드게임 추천- collusive payoff for the principal in this c트럼프 카드게임 추천siderably str트럼프 카드게임 추천g collusi트럼프 카드게임 추천-proof sense. The key issue is to guarantee the participati트럼프 카드게임 추천 of agents in an RCP mechanism. The proposed mechanism achieves this situati트럼프 카드게임 추천 by adding an opti트럼프 카드게임 추천 that each agent can exercise to protect himself against possible hold-up by his collusive partners.