# Tag Info

Accepted

### What is the difference between First-Visit Monte-Carlo and Every-Visit Monte-Carlo Policy Evaluation?

The first-visit and the every-visit Monte-Carlo (MC) algorithms are both used to solve the prediction problem (or, also called, "evaluation problem"), that is, the problem of estimating the value ...
• 33.8k
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### What is the proof that policy evaluation converges to the optimal solution?

First of all, efficiency and convergence are two different things. There's also the rate of convergence, so an algorithm may converge faster than another, so, in this sense, it may be more efficient. ...
• 33.8k

### Why can the Bellman equation be turned into an update rule?

Why are we allowed to convert the Bellman equations into update rules? There is a simple reason for this: convergence. The same chapter 4 of the same book mentions it. For example, in the case of ...
• 33.8k
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### Why is update rule of the value function different in policy evaluation and policy iteration?

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 ...
• 23.8k
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### Is the existence and uniqueness of the state-value function for $\gamma < 1$ theoretical?

In essence, your question is about convergence of infinite series. The mathematical discipline that studies such series is hundreds (if not thousands) years old an has nothing to do with "...
• 1,793

### Why do we need to go back to policy evaluation after policy improvement if the policy is not stable?

There is a difference between accurate value function estimates, and optimal value functions. An optimal value function is more specifically the value function of an optimal policy. Value functions ...
• 23.8k
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### Is value iteration stopped after one update of each state?

Where the author mentions the policy evaluation being stopped after one state, they are referring to the part of the algorithm that evaluates the policy -- the pseudocode you have listed is the ...
• 4,055
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### Why isn't the implementation of my policy evaluation for a simple MDP converging?

The issue is that in your list comprehension in def V_pi(state) you have ...
• 256
1 vote
Accepted

### Can we use Q-learning update for policy evaluation (not control)?

For off-policy learning you must have two policies - a behaviour policy and a target policy. If the two policies are the same, then you end up with SARSA, not Q learning. You cannot use Q learning ...
• 23.8k
1 vote
Accepted

### How can I implement policy evaluation when reward is tied to an action outcome?

The renowned book Reinforcement Learning: An Introduction (2nd edition), by Sutton and Barto, provides a different update rule than your first update rule for policy evaluation. Their update rule is ...
• 33.8k
1 vote

### Why can the Bellman equation be turned into an update rule?

To me, Bellman update is simply supervised learning: right hand side (bootstrap) is a sample of the left hand side (conditional expectation).. The Bellman equation simply explains that the right hand ...
• 131
1 vote
Accepted

### How does policy evaluation work for continuous state space model-free approaches?

How does policy evaluation work for continuous state space model-free approaches? ... Let's say you use a DQN to find another policy, how does model-free policy evaluation work then? Policy ...
• 928

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