The use of reinforcement learning has proven to be very promising for solving complex activities without human supervision during their learning process. However, their successful applications are predominantly focused on fictional and entertainment problems - such as games. Based on the above, this work aims to shed light on the application of reinforcement learning to solve this relevant real-world problem, the genome assembly. By expanding the only approach found in the literature that addresses this problem, we carefully explored the aspects of intelligent agent learning, performed by the Q-learning algorithm, to understand its suitability to be applied in scenarios whose characteristics are more similar to those faced by real genome projects. The improvements proposed here include changing the previously proposed reward system and including state space exploration optimization strategies based on dynamic pruning and mutual collaboration with evolutionary computing. These investigations were tried on 23 new environments with larger inputs than those used previously. All these environments are freely available on the internet for the evolution of this research by the scientific community. The results suggest consistent performance progress using the proposed improvements, however, they also demonstrate the limitations of them, especially related to the high dimensionality of state and action spaces. We also present, later, the paths that can be traced to tackle genome assembly efficiently in real scenarios considering recent, successfully reinforcement learning applications - including deep reinforcement learning - from other domains dealing with high-dimensional inputs.
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Monte Carlo Tree Search (MCTS) is a recently proposed search method that combines the precision of tree search with the generality of random sampling. It has received considerable interest due to its spectacular success in the difficult problem of computer Go, but has also proved beneficial in a range of other domains. This paper is a survey of the literature to date, intended to provide a snapshot of the state of the art after the first five years of MCTS research. We outline the core algorithm's derivation, impart some structure on the many variations and enhancements that have been proposed, and summarise the results from the key game and non-game domains to which MCTS methods have been applied. A number of open research questions indicate that the field is ripe for future work.
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蒙特卡洛树搜索(MCT)是设计游戏机器人或解决顺序决策问题的强大方法。该方法依赖于平衡探索和开发的智能树搜索。MCT以模拟的形式进行随机抽样,并存储动作的统计数据,以在每个随后的迭代中做出更有教育的选择。然而,该方法已成为组合游戏的最新技术,但是,在更复杂的游戏(例如那些具有较高的分支因素或实时系列的游戏)以及各种实用领域(例如,运输,日程安排或安全性)有效的MCT应用程序通常需要其与问题有关的修改或与其他技术集成。这种特定领域的修改和混合方法是本调查的主要重点。最后一项主要的MCT调查已于2012年发布。自发布以来出现的贡献特别感兴趣。
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在这项工作中,我们提出并评估了一种新的增强学习方法,紧凑体验重放(编者),它使用基于相似转换集的复发的预测目标值的时间差异学习,以及基于两个转换的经验重放的新方法记忆。我们的目标是减少在长期累计累计奖励的经纪人培训所需的经验。它与强化学习的相关性与少量观察结果有关,即它需要实现类似于文献中的相关方法获得的结果,这通常需要数百万视频框架来培训ATARI 2600游戏。我们举报了在八个挑战街机学习环境(ALE)挑战游戏中,为仅10万帧的培训试验和大约25,000次迭代的培训试验中报告了培训试验。我们还在与基线的同一游戏中具有相同的实验协议的DQN代理呈现结果。为了验证从较少数量的观察结果近似于良好的政策,我们还将其结果与从啤酒的基准上呈现的数百万帧中获得的结果进行比较。
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在过去的十年中,多智能经纪人强化学习(Marl)已经有了重大进展,但仍存在许多挑战,例如高样本复杂性和慢趋同稳定的政策,在广泛的部署之前需要克服,这是可能的。然而,在实践中,许多现实世界的环境已经部署了用于生成策略的次优或启发式方法。一个有趣的问题是如何最好地使用这些方法作为顾问,以帮助改善多代理领域的加强学习。在本文中,我们提供了一个原则的框架,用于将动作建议纳入多代理设置中的在线次优顾问。我们描述了在非传记通用随机游戏环境中提供多种智能强化代理(海军上将)的问题,并提出了两种新的基于Q学习的算法:海军上将决策(海军DM)和海军上将 - 顾问评估(Admiral-AE) ,这使我们能够通过适当地纳入顾问(Admiral-DM)的建议来改善学习,并评估顾问(Admiral-AE)的有效性。我们从理论上分析了算法,并在一般加上随机游戏中提供了关于他们学习的定点保证。此外,广泛的实验说明了这些算法:可以在各种环境中使用,具有对其他相关基线的有利相比的性能,可以扩展到大状态行动空间,并且对来自顾问的不良建议具有稳健性。
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2048 is a single-player stochastic puzzle game. This intriguing and addictive game has been popular worldwide and has attracted researchers to develop game-playing programs. Due to its simplicity and complexity, 2048 has become an interesting and challenging platform for evaluating the effectiveness of machine learning methods. This dissertation conducts comprehensive research on reinforcement learning and computer game algorithms for 2048. First, this dissertation proposes optimistic temporal difference learning, which significantly improves the quality of learning by employing optimistic initialization to encourage exploration for 2048. Furthermore, based on this approach, a state-of-the-art program for 2048 is developed, which achieves the highest performance among all learning-based programs, namely an average score of 625377 points and a rate of 72% for reaching 32768-tiles. Second, this dissertation investigates several techniques related to 2048, including the n-tuple network ensemble learning, Monte Carlo tree search, and deep reinforcement learning. These techniques are promising for further improving the performance of the current state-of-the-art program. Finally, this dissertation discusses pedagogical applications related to 2048 by proposing course designs and summarizing the teaching experience. The proposed course designs use 2048-like games as materials for beginners to learn reinforcement learning and computer game algorithms. The courses have been successfully applied to graduate-level students and received well by student feedback.
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机器学习算法中多个超参数的最佳设置是发出大多数可用数据的关键。为此目的,已经提出了几种方法,例如进化策略,随机搜索,贝叶斯优化和启发式拇指规则。在钢筋学习(RL)中,学习代理在与其环境交互时收集的数据的信息内容严重依赖于许多超参数的设置。因此,RL算法的用户必须依赖于基于搜索的优化方法,例如网格搜索或Nelder-Mead单简单算法,这对于大多数R1任务来说是非常效率的,显着减慢学习曲线和离开用户的速度有目的地偏见数据收集的负担。在这项工作中,为了使RL算法更加用户独立,提出了一种使用贝叶斯优化的自主超参数设置的新方法。来自过去剧集和不同的超参数值的数据通过执行行为克隆在元学习水平上使用,这有助于提高最大化获取功能的加强学习变体的有效性。此外,通过紧密地整合在加强学习代理设计中的贝叶斯优化,还减少了收敛到给定任务的最佳策略所需的状态转换的数量。与其他手动调整和基于优化的方法相比,计算实验显示了有希望的结果,这突出了改变算法超级参数来增加所生成数据的信息内容的好处。
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组合优化是运营研究和计算机科学领域的一个公认领域。直到最近,它的方法一直集中在孤立地解决问题实例,而忽略了它们通常源于实践中的相关数据分布。但是,近年来,人们对使用机器学习,尤其是图形神经网络(GNN)的兴趣激增,作为组合任务的关键构件,直接作为求解器或通过增强确切的求解器。GNN的电感偏差有效地编码了组合和关系输入,因为它们对排列和对输入稀疏性的意识的不变性。本文介绍了对这个新兴领域的最新主要进步的概念回顾,旨在优化和机器学习研究人员。
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在过去的十年中,深入的强化学习(DRL)算法已经越来越多地使用,以解决各种决策问题,例如自动驾驶和机器人技术。但是,这些算法在部署在安全至关重要的环境中时面临着巨大的挑战,因为它们经常表现出错误的行为,可能导致潜在的关键错误。评估DRL代理的安全性的一种方法是测试它们,以检测可能导致执行过程中严重失败的故障。这就提出了一个问题,即我们如何有效测试DRL政策以确保其正确性和遵守安全要求。测试DRL代理的大多数现有作品都使用扰动代理的对抗性攻击。但是,这种攻击通常会导致环境的不切实际状态。他们的主要目标是测试DRL代理的鲁棒性,而不是测试代理商在要求方面的合规性。由于DRL环境的巨大状态空间,测试执行的高成本以及DRL算法的黑盒性质,因此不可能对DRL代理进行详尽的测试。在本文中,我们提出了一种基于搜索的强化学习代理(Starla)的测试方法,以通过有效地在有限的测试预算中寻找无法执行的代理执行,以测试DRL代理的策略。我们使用机器学习模型和专用的遗传算法来缩小搜索错误的搜索。我们将Starla应用于深Q学习剂,该Qualla被广泛用作基准测试,并表明它通过检测到与代理商策略相关的更多故障来大大优于随机测试。我们还研究了如何使用我们的搜索结果提取表征DRL代理的错误事件的规则。这些规则可用于了解代理失败的条件,从而评估其部署风险。
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Machine learning frameworks such as Genetic Programming (GP) and Reinforcement Learning (RL) are gaining popularity in flow control. This work presents a comparative analysis of the two, bench-marking some of their most representative algorithms against global optimization techniques such as Bayesian Optimization (BO) and Lipschitz global optimization (LIPO). First, we review the general framework of the model-free control problem, bringing together all methods as black-box optimization problems. Then, we test the control algorithms on three test cases. These are (1) the stabilization of a nonlinear dynamical system featuring frequency cross-talk, (2) the wave cancellation from a Burgers' flow and (3) the drag reduction in a cylinder wake flow. We present a comprehensive comparison to illustrate their differences in exploration versus exploitation and their balance between `model capacity' in the control law definition versus `required complexity'. We believe that such a comparison paves the way toward the hybridization of the various methods, and we offer some perspective on their future development in the literature on flow control problems.
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The reinforcement learning paradigm is a popular way to address problems that have only limited environmental feedback, rather than correctly labeled examples, as is common in other machine learning contexts. While significant progress has been made to improve learning in a single task, the idea of transfer learning has only recently been applied to reinforcement learning tasks. The core idea of transfer is that experience gained in learning to perform one task can help improve learning performance in a related, but different, task. In this article we present a framework that classifies transfer learning methods in terms of their capabilities and goals, and then use it to survey the existing literature, as well as to suggest future directions for transfer learning work.
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This paper surveys the recent attempts, both from the machine learning and operations research communities, at leveraging machine learning to solve combinatorial optimization problems. Given the hard nature of these problems, state-of-the-art algorithms rely on handcrafted heuristics for making decisions that are otherwise too expensive to compute or mathematically not well defined. Thus, machine learning looks like a natural candidate to make such decisions in a more principled and optimized way. We advocate for pushing further the integration of machine learning and combinatorial optimization and detail a methodology to do so. A main point of the paper is seeing generic optimization problems as data points and inquiring what is the relevant distribution of problems to use for learning on a given task.
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This paper surveys the eld of reinforcement learning from a computer-science perspective. It is written to be accessible to researchers familiar with machine learning. Both the historical basis of the eld and a broad selection of current work are summarized. Reinforcement learning is the problem faced by an agent that learns behavior through trial-and-error interactions with a dynamic environment. The work described here has a resemblance to work in psychology, but di ers considerably in the details and in the use of the word \reinforcement." The paper discusses central issues of reinforcement learning, including trading o exploration and exploitation, establishing the foundations of the eld via Markov decision theory, learning from delayed reinforcement, constructing empirical models to accelerate learning, making use of generalization and hierarchy, and coping with hidden state. It concludes with a survey of some implemented systems and an assessment of the practical utility of current methods for reinforcement learning.
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近年来,机器学习的巨大进步已经开始对许多科学和技术的许多领域产生重大影响。在本文的文章中,我们探讨了量子技术如何从这项革命中受益。我们在说明性示例中展示了过去几年的科学家如何开始使用机器学习和更广泛的人工智能方法来分析量子测量,估计量子设备的参数,发现新的量子实验设置,协议和反馈策略,以及反馈策略,以及通常改善量子计算,量子通信和量子模拟的各个方面。我们重点介绍了公开挑战和未来的可能性,并在未来十年的一些投机愿景下得出结论。
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Deep reinforcement learning is poised to revolutionise the field of AI and represents a step towards building autonomous systems with a higher level understanding of the visual world. Currently, deep learning is enabling reinforcement learning to scale to problems that were previously intractable, such as learning to play video games directly from pixels. Deep reinforcement learning algorithms are also applied to robotics, allowing control policies for robots to be learned directly from camera inputs in the real world. In this survey, we begin with an introduction to the general field of reinforcement learning, then progress to the main streams of value-based and policybased methods. Our survey will cover central algorithms in deep reinforcement learning, including the deep Q-network, trust region policy optimisation, and asynchronous advantage actor-critic. In parallel, we highlight the unique advantages of deep neural networks, focusing on visual understanding via reinforcement learning. To conclude, we describe several current areas of research within the field.
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Safe Reinforcement Learning can be defined as the process of learning policies that maximize the expectation of the return in problems in which it is important to ensure reasonable system performance and/or respect safety constraints during the learning and/or deployment processes. We categorize and analyze two approaches of Safe Reinforcement Learning. The first is based on the modification of the optimality criterion, the classic discounted finite/infinite horizon, with a safety factor. The second is based on the modification of the exploration process through the incorporation of external knowledge or the guidance of a risk metric. We use the proposed classification to survey the existing literature, as well as suggesting future directions for Safe Reinforcement Learning.
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深度强化学习(RL)导致了许多最近和开创性的进步。但是,这些进步通常以培训的基础体系结构的规模增加以及用于训练它们的RL算法的复杂性提高,而均以增加规模的成本。这些增长反过来又使研究人员更难迅速原型新想法或复制已发表的RL算法。为了解决这些问题,这项工作描述了ACME,这是一个用于构建新型RL算法的框架,这些框架是专门设计的,用于启用使用简单的模块化组件构建的代理,这些组件可以在各种执行范围内使用。尽管ACME的主要目标是为算法开发提供一个框架,但第二个目标是提供重要或最先进算法的简单参考实现。这些实现既是对我们的设计决策的验证,也是对RL研究中可重复性的重要贡献。在这项工作中,我们描述了ACME内部做出的主要设计决策,并提供了有关如何使用其组件来实施各种算法的进一步详细信息。我们的实验为许多常见和最先进的算法提供了基准,并显示了如何为更大且更复杂的环境扩展这些算法。这突出了ACME的主要优点之一,即它可用于实现大型,分布式的RL算法,这些算法可以以较大的尺度运行,同时仍保持该实现的固有可读性。这项工作提出了第二篇文章的版本,恰好与模块化的增加相吻合,对离线,模仿和从演示算法学习以及作为ACME的一部分实现的各种新代理。
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Adequately assigning credit to actions for future outcomes based on their contributions is a long-standing open challenge in Reinforcement Learning. The assumptions of the most commonly used credit assignment method are disadvantageous in tasks where the effects of decisions are not immediately evident. Furthermore, this method can only evaluate actions that have been selected by the agent, making it highly inefficient. Still, no alternative methods have been widely adopted in the field. Hindsight Credit Assignment is a promising, but still unexplored candidate, which aims to solve the problems of both long-term and counterfactual credit assignment. In this thesis, we empirically investigate Hindsight Credit Assignment to identify its main benefits, and key points to improve. Then, we apply it to factored state representations, and in particular to state representations based on the causal structure of the environment. In this setting, we propose a variant of Hindsight Credit Assignment that effectively exploits a given causal structure. We show that our modification greatly decreases the workload of Hindsight Credit Assignment, making it more efficient and enabling it to outperform the baseline credit assignment method on various tasks. This opens the way to other methods based on given or learned causal structures.
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尽管深度强化学习(RL)最近取得了许多成功,但其方法仍然效率低下,这使得在数据方面解决了昂贵的许多问题。我们的目标是通过利用未标记的数据中的丰富监督信号来进行学习状态表示,以解决这一问题。本文介绍了三种不同的表示算法,可以访问传统RL算法使用的数据源的不同子集使用:(i)GRICA受到独立组件分析(ICA)的启发,并训练深层神经网络以输出统计独立的独立特征。输入。 Grica通过最大程度地减少每个功能与其他功能之间的相互信息来做到这一点。此外,格里卡仅需要未分类的环境状态。 (ii)潜在表示预测(LARP)还需要更多的上下文:除了要求状态作为输入外,它还需要先前的状态和连接它们的动作。该方法通过预测当前状态和行动的环境的下一个状态来学习状态表示。预测器与图形搜索算法一起使用。 (iii)重新培训通过训练深层神经网络来学习国家表示,以学习奖励功能的平滑版本。该表示形式用于预处理输入到深度RL,而奖励预测指标用于奖励成型。此方法仅需要环境中的状态奖励对学习表示表示。我们发现,每种方法都有其优势和缺点,并从我们的实验中得出结论,包括无监督的代表性学习在RL解决问题的管道中可以加快学习的速度。
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强化学习和最近的深度增强学习是解决如Markov决策过程建模的顺序决策问题的流行方法。问题和选择算法和超参数的RL建模需要仔细考虑,因为不同的配置可能需要完全不同的性能。这些考虑因素主要是RL专家的任务;然而,RL在研究人员和系统设计师不是RL专家的其他领域中逐渐变得流行。此外,许多建模决策,例如定义状态和动作空间,批次的大小和批量更新的频率以及时间戳的数量通常是手动进行的。由于这些原因,RL框架的自动化不同组成部分具有重要意义,近年来它引起了很多关注。自动RL提供了一个框架,其中RL的不同组件包括MDP建模,算法选择和超参数优化是自动建模和定义的。在本文中,我们探讨了可以在自动化RL中使用的文献和目前的工作。此外,我们讨论了Autorl中的挑战,打开问题和研究方向。
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