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1 answer
541 views

What are the similarities between Q-learning and Value Iteration?

This is the explanation of value iteration in our notes where you keep applying bellman optimality equation till it stops changing and then acting greedily wrt the value function gives the optimal ...
ace239's user avatar
  • 23
3 votes
2 answers
4k views

What is the difference between A2C and Q-Learning, and when to use one over the other?

I'm trying to get an accurate answer about the difference between A2C and Q-Learning. And when can we use each of them?
Hani's user avatar
  • 33
1 vote
1 answer
385 views

What is meant by "two action selections" in SARSA?

I have some difficulties understanding the difference between Q-learning and SARSA. Here (What are the differences between SARSA and Q-learning?) the following updating formulas are given: Q-Learning $...
PeterBe's user avatar
  • 266
6 votes
2 answers
8k views

When to use Value Iteration vs. Policy Iteration

Both value iteration and policy iteration are General Policy Iteration (GPI) algorithms. However, they differ in the mechanics of their updates. Policy Iteration seeks to first find a completed ...
SeeDerekEngineer's user avatar
17 votes
3 answers
13k views

What is the difference between Q-learning, Deep Q-learning and Deep Q-network?

Q-learning uses a table to store all state-action pairs. Q-learning is a model-free RL algorithm, so how could there be the one called Deep Q-learning, as deep means using DNN; or maybe the state-...
Dan D.'s user avatar
  • 1,318
5 votes
1 answer
511 views

Why does off-policy learning outperform on-policy learning?

I am self-studying about Reinforcement Learning using different online resources. I now have a basic understanding of how RL works. I saw this in a book: Q-learning is an off-policy learner. An off-...
Exploring's user avatar
  • 373
3 votes
1 answer
4k views

What are the differences between Q-Learning and A*?

Q-learning seems to be related to A*. I am wondering if there are (and what are) the differences between them.
Gonçalo Peres's user avatar
12 votes
1 answer
6k views

What exactly is the advantage of double DQN over DQN?

I started looking into the double DQN (DDQN). Apparently, the difference between DDQN and DQN is that in DDQN we use the main value network for action selection and the target network for outputting ...
Chukwudi's user avatar
  • 369
2 votes
1 answer
825 views

What are the differences between SARSA and Q-learning? [closed]

From Sutton and Barto's book Reinforcement Learning (Adaptive Computation and Machine Learning series), are the following definitions: To aid my learning of RL and gain an intuition, I'm focusing on ...
blue-sky's user avatar
  • 335
4 votes
1 answer
358 views

What is the difference between on-policy and off-policy for continuous environments?

I'm trying to understand RL applied to time series (so with infinite horizon) which have a continous state space and a discrete action space. First, some preliminary questions: in this case, what is ...
unter_983's user avatar
  • 331
11 votes
2 answers
2k views

Are Q-learning and SARSA the same when action selection is greedy?

I'm currently studying reinforcement learning and I'm having difficulties with question 6.12 in Sutton and Barto's book. Suppose action selection is greedy. Is Q-learning then exactly the same ...
hyuj's user avatar
  • 131
2 votes
1 answer
91 views

Do we need an explicit policy to sample $A'$ in order to compute the target in SARSA or Q-learning?

I would much appreciate if you could point me in the right direction regarding this question about targets for SARSA and Q-learning (notation: $S$ is the current state, $A$ is the current action, $R$ ...
Novak's user avatar
  • 123
2 votes
0 answers
92 views

What is the complexity of policy gradient algorithms compared to discrete action space algorithms?

I am using a policy gradient algorithm (actor-critic) for wireless networks. The policy gradient-based algorithm helps because it considers continuous action space. But how much does a policy ...
pratap's user avatar
  • 21
5 votes
2 answers
628 views

What is the difference between return and expected return?

At a time step $t$, for a state $S_{t}$, the return is defined as the discounted cumulative reward from that time step $t$. If an agent is following a policy (which in itself is a probability ...
digi philos's user avatar
47 votes
2 answers
26k views

What is the relation between Q-learning and policy gradients methods?

As far as I understand, Q-learning and policy gradients (PG) are the two major approaches used to solve RL problems. While Q-learning aims to predict the reward of a certain action taken in a certain ...
Tejas Ramdas's user avatar