Perfect Bayesian Equilibrium

Definition ∞ Perfect Bayesian Equilibrium is a solution concept in game theory applied to dynamic games with incomplete information, where players do not know all relevant details about each other. It requires that players’ strategies are optimal given their beliefs about other players’ types and past actions, and that these beliefs are updated consistently using Bayes’ rule. This concept ensures strategic rationality throughout the game, even at information sets that are never reached. It represents a refined form of Nash equilibrium for sequential games under uncertainty.
Context ∞ In the realm of blockchain and decentralized systems, perfect Bayesian equilibrium is a sophisticated analytical tool used to assess the robustness and security of complex protocols. News sometimes touches upon academic research or protocol design discussions where this concept helps evaluate the strategic behavior of participants in scenarios involving private information, such as certain consensus mechanisms or decentralized exchange designs. Understanding this equilibrium aids in predicting how rational actors will behave and whether a system can withstand various strategic manipulations.