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 Reinforcement Learning



Udacity Deep Reinforcement Learning Review- Is It Worth It? 2022

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Are you looking for Udacity Deep Reinforcement Learning Review?… If yes, first, read my latest Udacity Deep Reinforcement Learning Nanodegree Review and then decide whether to enroll or not in the program. Now, without any further ado, let's get started- Before starting the Udacity Deep Reinforcement Learning Review, I would like to mention one important thing regarding Udacity Deep Reinforcement Learning Nanodegree. Udacity Deep Reinforcement Learning Nanodegree is not for beginners. Yes, If you are a beginner with no previous knowledge of Python, Statistics, Machine Learning, and Its Frameworks(TensorFlow or Keras), I would not recommend you to enroll in this Nanodegree Program. Udacity Deep Reinforcement Learning Nanodegree is an advanced-level program and only suitable for those who have previously worked on Machine Learning and Deep Learning problems and know any Deep Learning framework such as TensorFlow, Keras, or PyTorch.


Fairness Based Energy-Efficient 3D Path Planning of a Portable Access Point: A Deep Reinforcement Learning Approach

arXiv.org Artificial Intelligence

In this work, we optimize the 3D trajectory of an unmanned aerial vehicle (UAV)-based portable access point (PAP) that provides wireless services to a set of ground nodes (GNs). Moreover, as per the Peukert effect, we consider pragmatic non-linear battery discharge for the battery of the UAV. Thus, we formulate the problem in a novel manner that represents the maximization of a fairness-based energy efficiency metric and is named fair energy efficiency (FEE). The FEE metric defines a system that lays importance on both the per-user service fairness and the energy efficiency of the PAP. The formulated problem takes the form of a non-convex problem with non-tractable constraints. To obtain a solution, we represent the problem as a Markov Decision Process (MDP) with continuous state and action spaces. Considering the complexity of the solution space, we use the twin delayed deep deterministic policy gradient (TD3) actor-critic deep reinforcement learning (DRL) framework to learn a policy that maximizes the FEE of the system. We perform two types of RL training to exhibit the effectiveness of our approach: the first (offline) approach keeps the positions of the GNs the same throughout the training phase; the second approach generalizes the learned policy to any arrangement of GNs by changing the positions of GNs after each training episode. Numerical evaluations show that neglecting the Peukert effect overestimates the air-time of the PAP and can be addressed by optimally selecting the PAP's flying speed. Moreover, the user fairness, energy efficiency, and hence the FEE value of the system can be improved by efficiently moving the PAP above the GNs. As such, we notice massive FEE improvements over baseline scenarios of up to 88.31%, 272.34%, and 318.13% for suburban, urban, and dense urban environments, respectively.


Edge-Compatible Reinforcement Learning for Recommendations

arXiv.org Artificial Intelligence

Most reinforcement learning (RL) recommendation systems designed for edge computing must either synchronize during recommendation selection or depend on an unprincipled patchwork collection of algorithms. In this work, we build on asynchronous coagent policy gradient algorithms \citep{kostas2020asynchronous} to propose a principled solution to this problem. The class of algorithms that we propose can be distributed over the internet and run asynchronously and in real-time. When a given edge fails to respond to a request for data with sufficient speed, this is not a problem; the algorithm is designed to function and learn in the edge setting, and network issues are part of this setting. The result is a principled, theoretically grounded RL algorithm designed to be distributed in and learn in this asynchronous environment. In this work, we describe this algorithm and a proposed class of architectures in detail, and demonstrate that they work well in practice in the asynchronous setting, even as the network quality degrades.


Continual Machine Reading Comprehension via Uncertainty-aware Fixed Memory and Adversarial Domain Adaptation

arXiv.org Artificial Intelligence

Continual Machine Reading Comprehension aims to incrementally learn from a continuous data stream across time without access the previous seen data, which is crucial for the development of real-world MRC systems. However, it is a great challenge to learn a new domain incrementally without catastrophically forgetting previous knowledge. In this paper, MA-MRC, a continual MRC model with uncertainty-aware fixed Memory and Adversarial domain adaptation, is proposed. In MA-MRC, a fixed size memory stores a small number of samples in previous domain data along with an uncertainty-aware updating strategy when new domain data arrives. For incremental learning, MA-MRC not only keeps a stable understanding by learning both memory and new domain data, but also makes full use of the domain adaptation relationship between them by adversarial learning strategy. The experimental results show that MA-MRC is superior to strong baselines and has a substantial incremental learning ability without catastrophically forgetting under two different continual MRC settings.


Multi-Task Fusion via Reinforcement Learning for Long-Term User Satisfaction in Recommender Systems

arXiv.org Artificial Intelligence

Recommender System (RS) is an important online application that affects billions of users every day. The mainstream RS ranking framework is composed of two parts: a Multi-Task Learning model (MTL) that predicts various user feedback, i.e., clicks, likes, sharings, and a Multi-Task Fusion model (MTF) that combines the multi-task outputs into one final ranking score with respect to user satisfaction. There has not been much research on the fusion model while it has great impact on the final recommendation as the last crucial process of the ranking. To optimize long-term user satisfaction rather than obtain instant returns greedily, we formulate MTF task as Markov Decision Process (MDP) within a recommendation session and propose a Batch Reinforcement Learning (RL) based Multi-Task Fusion framework (BatchRL-MTF) that includes a Batch RL framework and an online exploration. The former exploits Batch RL to learn an optimal recommendation policy from the fixed batch data offline for long-term user satisfaction, while the latter explores potential high-value actions online to break through the local optimal dilemma. With a comprehensive investigation on user behaviors, we model the user satisfaction reward with subtle heuristics from two aspects of user stickiness and user activeness. Finally, we conduct extensive experiments on a billion-sample level real-world dataset to show the effectiveness of our model. We propose a conservative offline policy estimator (Conservative-OPEstimator) to test our model offline. Furthermore, we take online experiments in a real recommendation environment to compare performance of different models. As one of few Batch RL researches applied in MTF task successfully, our model has also been deployed on a large-scale industrial short video platform, serving hundreds of millions of users.


Tianshou: a Highly Modularized Deep Reinforcement Learning Library

arXiv.org Artificial Intelligence

In this paper, we present Tianshou, a highly modularized Python library for deep reinforcement learning (DRL) that uses PyTorch as its backend. Tianshou intends to be research-friendly by providing a flexible and reliable infrastructure of DRL algorithms. It supports online and offline training with more than 20 classic algorithms through a unified interface. To facilitate related research and prove Tianshou's reliability, we have released Tianshou's benchmark of MuJoCo environments, covering eight classic algorithms with state-of-the-art performance. We open-sourced Tianshou at https://github.com/thu-ml/tianshou/.


Learning Two-Player Mixture Markov Games: Kernel Function Approximation and Correlated Equilibrium

arXiv.org Artificial Intelligence

We consider learning Nash equilibria in two-player zero-sum Markov Games with nonlinear function approximation, where the action-value function is approximated by a function in a Reproducing Kernel Hilbert Space (RKHS). The key challenge is how to do exploration in the high-dimensional function space. We propose a novel online learning algorithm to find a Nash equilibrium by minimizing the duality gap. At the core of our algorithms are upper and lower confidence bounds that are derived based on the principle of optimism in the face of uncertainty. We prove that our algorithm is able to attain an $O(\sqrt{T})$ regret with polynomial computational complexity, under very mild assumptions on the reward function and the underlying dynamic of the Markov Games. We also propose several extensions of our algorithm, including an algorithm with Bernstein-type bonus that can achieve a tighter regret bound, and another algorithm for model misspecification that can be applied to neural function approximation.


Machine Learning Concepts

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Everything you need to know about Reinforcement LearningApril 4, 2022 The phrase "Reinforcement Learning" could sound a little intimidating at first, but when we break it down, it's actually quite simple. Let's start with the phrase itself. It simply means to strengthen or support something. The phrase "Reinforcement Learning" could sound a little intimidating at first, but when we break it down, it's actually quite simple. Let's start with the phrase itself.


Using AI Chips To Design Better AI Chips

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Chip design is as much of an art as it is an engineering feat. With all of the possible layouts of logic and memory blocks and the wires linking them, there are a seemingly infinite placement combinations and often, believe it or not, the best people at chip floorplans are working from experience and hunches and they can't always give you a good answer as to why a particular pattern works and others don't. The stakes are high in chip design, and researchers have been trying to take the human guesswork out of this chip layout task and to drive toward more optimal designs. The task doesn't go away as we move towards chiplet designs, either, since all of those chiplets on a compute engine will need to be interconnected to be a virtual monolithic chip and all of the latencies and power consumption will have to be taken into effect for such circuit complexes. This is a natural job, it would seem, for AI techniques to help in chip design.