Games in Public Announcement: How to Reduce System Losses in Optimistic Blockchain Mechanisms
Siyuan Liu, Yulong Zeng
TL;DR
The paper develops a game-theoretic model of announcement games in optimistic Layer-2 rollups, framing interaction between an Aggregator and Validators with deposits, rewards, and penalties. It derives a complete set of Nash equilibria across one, two, and N validators, including symmetric and asymmetric cases, and provides explicit loss expressions such as $\mathcal{L}=\beta(1-\alpha)Z$, illustrating how losses grow with the final block value $Z$ and change with system parameters. Through both analytical results and parameter analysis, it shows how compactly tuning deposits, rewards, and costs (and introducing a tie-breaking term $D$) can move the system toward lower-loss equilibria, including non-KYC variants. The work yields practical mechanism-design guidelines for reducing system losses in optimistic rollups and similar information-disclosure games, with insights into the trade-offs between security incentives, validator participation, and throughput. Overall, the results illuminate incentive-compatibility considerations for scalable, secure L2 architectures and offer concrete levers for protocol designers.
Abstract
Announcement games, where information is disseminated by announcers and challenged by validators, are prevalent in real-world scenarios. Validators take effort to verify the validity of the announcements, gaining rewards for successfully challenging invalid ones, while receiving nothing for valid ones. Optimistic Rollup, a Layer 2 blockchain scaling solution, exemplifies such games, offering significant improvements in transaction throughput and cost efficiency. We present a game-theoretic model of announcement games to analyze the potential behaviors of announcers and validators. We identify all Nash equilibria and study the corresponding system losses for different Nash equilibria. Additionally, we analyze the impact of various system parameters on system loss under the Nash equilibrium. Finally, we provide suggestions for mechanism optimization to reduce system losses.
