论文标题
具有虚拟回报的联盟安全平衡
Coalition-Safe Equilibria with Virtual Payoffs
论文作者
论文摘要
考虑一组被邀请执行协议$π$的政党。该协议将在最后（或定期间隔）时产生某些费用，它将填充和更新为参与者分配（虚拟）奖励的本地表。每个参与者都渴望抵消协议过程中提供的这些虚拟回报的参与成本。在这种情况下，我们介绍并研究了联盟安全均衡的概念。特别是，我们考虑了一个参与者组成的战略联盟，该联盟是由中央协调的，并有可能与$π$偏离$π$，目的是增加其{\ em至少一个其他参与者的观点的效用。如果没有这种协议偏差，则协议$π$称为具有虚拟回报的联盟安全平衡（EVP）。我们将概念应用于研究区块方案中的激励措施。我们开始使用框架来提供比特币区块链中激励措施的统一图片，用于基于基于奖励的实用性功能，并证明了Fruitchain区块链协议激励措施[PODC 2017]的新成果，表明平衡条件可用于基于绝对的$ N-1 $ N-1 $ N-1 $ nimbaltions oblesions usistions usistions usextions useversions usextions $ n-1 $ n/2 $ n/2 $ 2后者的结果持有任何“弱公平”区块链协议，这是我们引入的新财产，并且可能具有独立的兴趣。
Consider a set of parties invited to execute a protocol $Π$. The protocol will incur some cost to run while in the end (or at regular intervals), it will populate and update local tables that assign (virtual) rewards to participants. Each participant aspires to offset the costs of participation by these virtual payoffs that are provided in the course of the protocol. In this setting, we introduce and study a notion of coalition-safe equilibrium. In particular, we consider a strategic coalition of participants that is centrally coordinated and potentially deviates from $Π$ with the objective to increase its utility with respect to the view of {\em at least one} of the other participants. The protocol $Π$ is called a coalition-safe equilibrium with virtual payoffs (EVP) if no such protocol deviation exists. We apply our notion to study incentives in blockchain protocols. We proceed to use our framework to provide a unified picture of incentives in the Bitcoin blockchain, for absolute and relative rewards based utility functions, as well as prove novel results regarding incentives of the Fruitchain blockchain protocol [PODC 2017] showing that the equilibrium condition holds for collusions up to $n-1$ players for absolute rewards based utility functions and less than $n/2$ for relative rewards based utility functions, with the latter result holding for any "weakly fair" blockchain protocol, a new property that we introduce and may be of independent interest.
