# Tag Info

## Hot answers tagged dynamic-programming

4

Yes, the two update equations are equivalent. As an aside, technically the equation you give is not the Bellman equation, but the update step re-written as an equation - in the Bellman equation instead of $v_{k+1}(s)$ or $v_{k}(s)$ (showing iterations of approximate value functions), you would have $v_{\pi}(s)$ (representing the true value of a state under ...

3

There is one thing I don't particularly understand. Why do we need the state-transition probability function when calculating the importance sampling ratio for off-policy prediction? It is not needed for calculation. It must be included in the theory, to compare the correct probability of each trajectory (on-policy vs off-policy). However, the state ...

3

The basis of Q-learning is recursive (similar to dynamic programming), where only the absolute value of the terminal state is known. This may be true in some environments. Many environments do not have a terminal state, they are continuous. Your statement may be true for instance in a board game environment where the goal is to win, but it is false for e.g. ...

2

The term you're looking for is "replacement schemes". As far as I'm aware, the primary reference on this is still Replacement Schemes for Transposition Tables, although it is a fairly old paper from 1994. I'll very briefly summarize the seven different schemes listed in this paper, but full text of the paper is also freely available and contains more info: ...

2

You can obtain the optimal policy from the optimal state value function if you also have the state transition and reward model for the environment $p(s',r|s,a)$ - the probability of receiving reward $r$ and arriving in state $s'$ when starting in state $s$ and taking action $a$. This looks like: \pi^*(s) = \text{argmax}_a [\sum_{s',r} p(s',r|s,a)(r + \...

1

The core problem here is state representation, not estimating return due to delayed response to actions on the original state representation (which is no longer complete for the new problem). If you fix that, then you can solve your problem as a normal MDP, and base calculations on single timesteps. This allows you to continue using dynamic programming to ...

1

A full Bellman update can be intractable. For instance, if your state space or action space are continuous, the full Bellman update is intractable. You can try to solve this by discretizing, but if your state space is large this will also be intractable.

1

If you have enough domain knowledge to be able to reliably, intentionally reach those terminal states often when generating experience, yeah, that could help. Generally, the assumption in Reinforcement Learning is no domain knowledge other than the assumption that we're in a Markov Decision Process. This means we start learning from scratch, and before ...

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