What is Double Deep Q-Network (DDQN) and why is it better than DQN?

Updated May 17, 2026

Short answer

DDQN reduces overestimation bias by separating action selection and evaluation.

Deep explanation

In DQN, the same network selects and evaluates actions, causing overoptimistic Q-values. DDQN fixes this by using the online network for action selection and the target network for evaluation, improving stability and performance.

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