Trust Region
Trust region methods are optimization techniques that constrain updates to a region around a current solution, ensuring stability and preventing drastic changes during iterative optimization processes. Current research focuses on improving the efficiency and robustness of these methods, particularly within deep learning (e.g., using adaptive trust region mechanisms and diagonal approximations of Hessian matrices) and reinforcement learning (e.g., employing trust regions with KL divergence, Wasserstein distance, or CVaR constraints). These advancements are significantly impacting various fields, enabling faster and more reliable training of large-scale models, safer reinforcement learning agents, and more efficient solutions to complex optimization problems in diverse applications.