On amending the Maskin's sufficiency theorem by using complex numbers

The Maskin's theorem is a fundamental work in the theory of mechanism design. In this paper, we will propose a self-enforcing agreement by which agents can fight a bad social choice rule which satisfies monotonicity and no-veto if an additional condition is satisfied. The agreement is based on complex numbers and is justified if the designer receives messages from the agents through some communication channels (e.g., Internet). Under the assumption of complete information among agents, the designer cannot prevent the agents from signing such agreement. Thereby, the Maskin's sufficiency theorem is amended.