Hacker News new | ask | show | jobs
by hideo7746 2006 days ago
On one hand you're right, methods like Q-learning are model-free and do not necessarily encode much about state dynamics. The Q-function is a feature (function) of state and while ita may not say much about the model, it does encode the most important aspect of the model in terms of solving the task. Namely, it predicts the accumulated reward conditional on next actions actions. That makes it a somewhat narrow representation of state on its own. But, if you consider an environment that has many reward signals, and you learn Q functions for each, this ensemble of Q functions can consitute a rich representation of state. Depending on what the reward functions are, the associated Q functions may be sufficient to construct a full model. so I guess my point is that the learned quantities in RL encode key aspects of state, and when you expand beyond the single task/single reward RL setting the lines between value and model can become blurred.