Questions tagged [reinforcement-learning]

For questions related to reinforcement learning, i.e. a machine learning technique where we imagine an agent that interacts with an environment (composed of states) in time steps by taking actions and receiving rewards (or reinforcements), then, based on these interactions, the agent tries to find a policy (i.e. a behavioural strategy) that maximizes the cumulative reward (in the long run), so the goal of the agent is to maximize the reward.

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42 views

What is the gradient of the Q function with respect to the policy's parameters?

I have been recently studying Actor-Critic algorithms, and I ran into the following question. Let $Q_{\omega}$ be the critic network, and $\pi_{\theta}$ be the actor. It is known that in order to ...
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How are the classical MDP and the object-oriented MDP views different?

I've been reading the attached paper - which aims to model entities in the world as objects, including the learning agent itself! To say the least, the goal is to navigate through what seems like a ...
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1answer
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How can I sample the output distribution multiple times when pruning the filters with reinforcement learning?

I was reading the paper Learning to Prune Filters in Convolutional Neural Networks, which is about pruning the CNN filters using reinforcement learning (policy gradient). The paper says that the input ...
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29 views

How should I design a reward function for a NLP problem where two models interoperate?

I would like to design a reward function. I am training two models from the first model that classify set of texts (paragraphs and keywords) and I also got some hidden states. The second model is ...
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40 views

Action masking for on policy algorithm like PPO

I have an environment, in which my agent learns according to PPO. The environment has a maximum of 80 actions, however not all of them are always allowed. My idea was to mask them, by setting the ...
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29 views

How can I formalise a non-zero-sum game of $N$ agent as Markov game?

I coded a non-zero-sum game of $N$ agents in a discrete dynamic environment to RL with Q-learning and DQN agents. It's like a marathon. Only two actions are available per agent: $\{ G \text{ (move ...
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42 views

Is Mean Squared Error Loss function a good loss function for continuous variables $0 < x < 1$

Suppose I am utilising a neural network to predict the next state, $s'$ based on the current $(s, a)$ pairs. all my neural network inputs are between 0 and 1 and the loss function for this network ...
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33 views

How was the DQN trained to play many games?

Some people claim that DQN was used to play many Atari games. But what actually happened? Was DQN trained only once (with some data from all games) or was it trained separately for each game? What was ...
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How to formulate normalization/probability conditions on state-action spaces in Gym?

I intend to develop a custom environment for open-ai's gym. My goal is for an agent to learn (among additional objectives) dividing a certain quantity drawn from a continous action space (i.e. spaces....
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How should I define the reward function for the Connect Four game?

I'm creating an RL application for the game Connect Four. I've researched the different strategies for the game and which positions are more favourable to lead to a win. Should I be assigning ...
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171 views

How much time does it take to train DQN on Atari environment?

I am trying to build a DQN model for the Atari Pong game, but I am not sure whether the model is learning at all. I am using the architecture described in the paper Playing Atari with Deep ...
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Why is my DQN model not getting better?

I've created a deep Q network. My model does not get better, and can't see what I'm doing wrong. I'm new to RL. Replay Memory ...
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64 views

Policy Gradient Reward Oscillation in MATLAB

I'm trying to train a Policy Gradient Agent with Baseline for my RL research. I'm using the in-built RL toolbox from MATLAB (https://www.mathworks.com/help/reinforcement-learning/ug/pg-agents.html) ...
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85 views

How to correctly implement self-play with DQN?

I have an environment where an agent faces an equal opponent, and while I've achieved OK performance implementing DQN and treating the opponent as a part of the environment, I think performance would ...
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28 views

How to draw backup diagram when reward is in expectation but next state is iterated?

I am working through Sutton and Barto's RL book. So far in the text, when backup diagrams are drawn, the reward and next state are iterated together (i.e. the equations always have $\sum_{s',r}$), ...
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43 views

Should the RL agent be trained in an environment with real-world data or with a synthetic model?

I want to train a reinforcement learning agent in an environment with parameters (for example, the wind speed, sun irradiation, etc.) that change over time. I have recorded a limited amount of data ...
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1answer
59 views

How can I implement the reward function for an 8-DOF robot arm with TRPO?

I need to get an 8-DOF (degrees of freedom) robot arm to move a specified point. I need to implement the TRPO RL code using OpenAI gym. I already have the gazebo environment. But I am unsure of how to ...
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44 views

How does adding noise to the action in DDPG help in learning?

I can't understand how playing with the action generated by the actor network in DDPG by adding the noise term helps in exploration.
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Evaluation a policy learned using Q - learning

I have been reading literature on reinforcement learning in healthcare. I am slightly confused between the policy evaluation for both SARSA and Q-learning. To my knowledge, I believe that SARSA is ...
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58 views

Formulation of a Markov Decision Process Problem

Given a list of $N$ questions. If question $i$ is answered correctly (given probability $p_i$), we receive reward $R_i$; if not the quiz terminates. Find the optimal order of questions to maximize ...
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1answer
83 views

How can I perform lane detection with reinforcement learning?

I'm quite new to reinforcement learning and my project will consist of detecting lanes with RL. I'm using q-learning and I'm having a hard time thinking how my q table should look like, I mean - ...
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What effect does increasing the actions in RL have?

Consider a 2D snake game, where the snake has to eat food to become longer. It must avoid hitting walls and biting into her tail. Such a game could have a different amount of actions: 3 actions: go ...
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1answer
87 views

Reinforcement Learning Continuous Control (DDPG): How to avoid thrashing of issued actions? How to reward smooth output over flittering?

Currently I'm working on a continuous state / continuous action controller. It shall control a certain roll angle of an aircraft by issuing the correct aileron commands (between -1...1 continuous). ...
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How does the update rule for the one-step actor-critic method work?

Can you please elucidate the math behind the update rule for the critic? I've seen in other places that just a squared distance of $R + \hat{v}(S', w) - \hat{v}(S,w)$ is used, but Sutton suggests an ...
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39 views

Can the importance sampling estimator have a non-stationary behaviour policy even if the target policy is stationary?

The inverse propensity score (IPS) estimator, which is used for off-policy evaluation in a contextual bandit problem, is well explained in the paper Doubly Robust Policy Evaluation and Optimization. ...
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Why is this Monte Carlo approach scalable for a growing number of states variables and action variables?

I am reading a research paper on the formulation of MDP problems to ICU treatment decision making: Treatment Recommendation in Critical Care: A Scalable and Interpretable Approach in Partially ...
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1answer
65 views

NoisyNet DQN with default parameters not exploring

I implemented a DQN algorithm that plays OpenAIs Cartpole environment. The NN architecture consists of 3 normal linear layers that encode the state, and one noisy linear layer, that predicts the Q ...
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Can we use imitation learning for on-policy algorithms?

Imitation learning uses experiences of an (expert) agent to train another agent, in my understanding. If I want to use an on-policy algorithm, for example, Proximal Policy Optimization, because of it'...
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What are some approaches to estimate the transition and observation probabilities in POMDP?

What are some common approaches to estimate the transition or observation probabilities, when the probabilities are not exactly known? When realizing a POMDP model, the state model needs additional ...
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What form of output would be needed to train a model on a connect 4 AI?

I've had a big interest in machine learning for a while, and I've followed along a few tutorials, but have never made my own project. After losing many games of connect 4 with my friends, I decided to ...
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How would one develop an action space for a game that is proprietary?

I'm currently trying to develop an RL that will teach itself to play the popular fighting game "Tekken 7". I initially had the idea of teaching it to play generally- against actual opponents with ...
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How to set the multiple continuous actions with constraints

I want to build a Deep Reinforcement Learning Model for Asset allocation. Background: I have 7 stock indexes from different markets, and I want to build a policy to produce the action (likes whether ...
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What could be the cause of the drop of the total reward when using DQN to solve the cart-pole environment?

I'm trying to use DQN to solve the cart-pole environment. I have 2 networks (target and behavior). Both of them have 3 hidden layers with 24 neurons, using the ReLU activation. The loss is MSE and the ...
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Finding total number of states in a POMDP

I've been working on a question that is posed in a document I've been reading, that models qualifying for a job as a POMDP. In this model, a person takes 3 exams, and must pass all of them in order to ...
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23 views

How to learn using DDPG in python solely using a timeseries datasets

I have a lengthy timeseries datasets which contains several variables (from sensors etc) to be classified as actions or states. Providing they are successfully done, I want to learn a control policy ...
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33 views

Best approach for online Machine Translation with few hundred of samples?

I want to implement a model that improves itself with the passage of time. My main task is to build a machine translator (from English to Urdu).. The problem I am facing is that I have very little ...
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98 views

how to use Softmax action selection algorithm in atari-like game

I'm currently writing a program using keras (python 3) to play a game similar to Atari games, only in this one there are objects moving in the screen in different angles and directions (in most of ...
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1answer
287 views

What are the pros and cons of using standard deviation or entropy for exploration in PPO?

When trying to implement my own PPO (Proximal Policy Optimizer), I came across two different implementations : Exploration with std Collect trajectories on $N$ timesteps, by using a policy-centered ...
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Loss reduction, but constant performance with CNN

I made a CNN with a reasonable loss curve, but the performance of the model does not improve. I have tried making the model larger, I am using three convolutional layers with batch norms. Thanks for ...
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51 views

Torch CNN not training

I am completely new to CNN's, and I do not quite know how to design or use them efficiently. That being said, I am attempting to build a CNN that learns to play Pac-man with reinforcement learning. I ...
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28 views

Developmental systems that try to explain or understand the reward value in the reinforcement learning?

Are there methods (possibly logical or (how they are called in the literature) relational) that allows for the developmental systems to understand or explain the value of the received reward during ...
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How to show Monte Carlo methods converge to an estimate which minimizes mean squared error?

In chapter six of Sutton and Barto (p.128), they claim Monte Carlo methods converge to an estimate minimizing the mean squared error. How can this be shown formally? Bump
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Is it possible to use Reward Function of type R(s, a, s') if more than one action is applied?

I am applying a reinforcement learning agent (PPO2, stable baselines implementation) to a custom built environment using OpenAI Gym. One reward function (formualted as loss function, that is, all ...
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What is a high performing network architecture to use in a PPO2 MlpLnLstmPolicy RL model?

I am playing around with creating custom architectures in stable-baselines. Specifically I am training an agent using a PPO2 model. My question is, are there some rules of thumb or best practices in ...
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21 views

Why do these reward functions give different training curves?

Let's say our task is to pick and place a block, like: https://gym.openai.com/envs/FetchPickAndPlace-v0/ Reward function 1: -1 for block not placed, 0 for block placed Reward function 2: 0 for block ...
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36 views

How to solve optimal control problem with reinforcement learning

The problem I am trying to attack is a predator-prey pursuit problem. There are multiple predators that pursue multiple preys and preys tried to evade predators. I am trying to solve a simplified ...
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79 views

Coloring graphs with reinforcement learning

I am trying to build an RL agent to solve the NP-hard problem graph coloring. The problem is quite challenging. This how I addressed it. The environment To preserve the scalability of the ...
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59 views

What is the meaning of the words 'bias' and 'variance' in RL?

In algorithms like MC/TD (tabular value approximation) two of the metrics used to measure their performance are the bias and the variance. What do these terms mean? And which characteristic of the ...
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104 views

What is ratio of the objective function in the case of continuous action spaces?

I'm trying to implement the proximal policy optimization (PPO) algorithm. I'm confused on how to make it work with continuous action space. For discrete action space, the output of the network is the ...
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39 views

Will the RL agent implemented as a neural network fine-tune itself?

Normally, when you develop a neural network, train it for object recognition (on normal objects like bike, car, plane, dog, cloud, etc.), and it turns out to perform very well, you would like to fine-...

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