π€ AI Summary
This work addresses the challenge of safely exploiting subtle or diffuse opponent deviations in two-player zero-sum imperfect-information games without exposing exploitable weaknesses. The authors propose a safe opponent exploitation framework that employs anytime-valid confidence sequences to detect statistically significant deviations from equilibrium in real time, constructs a conservative opponent model, and computes a restricted response within a discretized strategy space. Prior to deployment, candidate strategies undergo full-game-tree best-response verification to generate safety certificates tied to the actual deployed policy, thereby decoupling model quality from safety loss. This mechanism enables agents to autonomously audit their own safety with verifiable guarantees. Experiments demonstrate steady-state payoffs 6.2Γ higher than baseline in Leduc Holdβem and trajectory-mixed strategies yielding 13.6Γ improvement; across 36,000 hands in Leduc, Liarβs Dice, and 5-rank Leduc, all results satisfy certificate tolerances.
π Abstract
An agent playing a Nash-equilibrium strategy in a two-player zero-sum imperfect-information game secures the game value but forfeits the additional value offered by a flawed opponent. Diffuse deviations pose a particular challenge: binary release rules may gather too little evidence to act, while a full best response to an incomplete opponent model can be highly exploitable. We introduce \emph{budget-constrained confidence-scheduled restricted responses} (CS-RNR), the first opponent-exploitation method whose safety guarantee is a certificate the agent computes on the strategy it actually deploys, so that every exploit it commits to is one it has audited itself. The method tracks pooled action frequencies with anytime-valid confidence sequences and treats a frequency as exploitable only once its interval separates from an equilibrium reference. The confirmed deviations define a conservative opponent model, which a restricted-response solve turns into candidate counter-strategies over a grid of pin levels. Before deployment, each complete candidate is evaluated by a full-tree best response. The resulting certificate is compared with a user-specified budget and committed atomically with the strategy. Because this check is performed on the played strategy, model quality determines the exploitation achieved while the certificate controls reference-relative expected loss. In Leduc hold'em, CS-RNR obtains $6.2\times$ the steady-state gain of a money-verified binary gate while keeping every deployed strategy within budget. A trajectory mixture using the same estimator reaches $13.6\times$ the budget. Across Leduc, Liar's Dice, and 5-rank Leduc, all $36{,}000$ audited hands satisfy the reported certificate tolerance.