Single Policy Concentrability
Single policy concentrability is a key assumption in offline reinforcement learning (RL), focusing on ensuring that the offline dataset sufficiently covers the state-action space visited by the target policy. Current research emphasizes developing provably efficient algorithms under this assumption, often employing primal-dual methods, marginalized importance sampling, or pessimism-based approaches within actor-critic frameworks. This focus stems from the need to address the challenge of partial data coverage in offline RL, enabling reliable learning of optimal policies from limited historical data. Advances in this area are crucial for making offline RL more practical and applicable to real-world scenarios where extensive online data collection is infeasible or costly.