A critical challenge in multi-agent reinforcement learning(MARL) is for multiple agents to efficiently accomplish complex, long-horizon tasks. The agents often have difficulties in cooperating on common goals, dividing complex tasks, and planning through several stages to make progress. We propose to address these challenges by guiding agents with programs designed for parallelization, since programs as a representation contain rich structural and semantic information, and are widely used as abstractions for long-horizon tasks. Specifically, we introduce Efficient Multi-Agent Reinforcement Learning with Parallel Program Guidance(E-MAPP), a novel framework that leverages parallel programs to guide multiple agents to efficiently accomplish goals that require planning over $10+$ stages. E-MAPP integrates the structural information from a parallel program, promotes the cooperative behaviors grounded in program semantics, and improves the time efficiency via a task allocator. We conduct extensive experiments on a series of challenging, long-horizon cooperative tasks in the Overcooked environment. Results show that E-MAPP outperforms strong baselines in terms of the completion rate, time efficiency, and zero-shot generalization ability by a large margin.

最先进的多机构增强学习（MARL）方法为各种复杂问题提供了有希望的解决方案。然而，这些方法都假定代理执行同步的原始操作执行，因此它们不能真正可扩展到长期胜利的真实世界多代理/机器人任务，这些任务固有地要求代理/机器人以异步的理由，涉及有关高级动作选择的理由。不同的时间。宏观行动分散的部分可观察到的马尔可夫决策过程（MACDEC-POMDP）是在完全合作的多代理任务中不确定的异步决策的一般形式化。在本论文中，我们首先提出了MacDec-Pomdps的一组基于价值的RL方法，其中允许代理在三个范式中使用宏观成果功能执行异步学习和决策：分散学习和控制，集中学习，集中学习和控制，以及分散执行的集中培训（CTDE）。在上述工作的基础上，我们在三个训练范式下制定了一组基于宏观行动的策略梯度算法，在该训练范式下，允许代理以异步方式直接优化其参数化策略。我们在模拟和真实的机器人中评估了我们的方法。经验结果证明了我们在大型多代理问题中的方法的优势，并验证了我们算法在学习具有宏观actions的高质量和异步溶液方面的有效性。

Transformer, originally devised for natural language processing, has also attested significant success in computer vision. Thanks to its super expressive power, researchers are investigating ways to deploy transformers to reinforcement learning (RL) and the transformer-based models have manifested their potential in representative RL benchmarks. In this paper, we collect and dissect recent advances on transforming RL by transformer (transformer-based RL or TRL), in order to explore its development trajectory and future trend. We group existing developments in two categories: architecture enhancement and trajectory optimization, and examine the main applications of TRL in robotic manipulation, text-based games, navigation and autonomous driving. For architecture enhancement, these methods consider how to apply the powerful transformer structure to RL problems under the traditional RL framework, which model agents and environments much more precisely than deep RL methods, but they are still limited by the inherent defects of traditional RL algorithms, such as bootstrapping and "deadly triad". For trajectory optimization, these methods treat RL problems as sequence modeling and train a joint state-action model over entire trajectories under the behavior cloning framework, which are able to extract policies from static datasets and fully use the long-sequence modeling capability of the transformer. Given these advancements, extensions and challenges in TRL are reviewed and proposals about future direction are discussed. We hope that this survey can provide a detailed introduction to TRL and motivate future research in this rapidly developing field.

Recently, model-based agents have achieved better performance than model-free ones using the same computational budget and training time in single-agent environments. However, due to the complexity of multi-agent systems, it is tough to learn the model of the environment. The significant compounding error may hinder the learning process when model-based methods are applied to multi-agent tasks. This paper proposes an implicit model-based multi-agent reinforcement learning method based on value decomposition methods. Under this method, agents can interact with the learned virtual environment and evaluate the current state value according to imagined future states in the latent space, making agents have the foresight. Our approach can be applied to any multi-agent value decomposition method. The experimental results show that our method improves the sample efficiency in different partially observable Markov decision process domains.

将有用的背景知识传达给加强学习（RL）代理是加速学习的重要方法。我们介绍了Rlang，这是一种特定领域的语言（DSL），用于将域知识传达给RL代理。与RL社区提出的其他现有DSL不同，该基础是决策形式主义的单个要素（例如，奖励功能或政策功能），RLANG可以指定有关马尔可夫决策过程中每个元素的信息。我们为rlang定义了精确的语法和基础语义，并提供了解析器实施，将rlang程序基于算法 - 敏捷的部分世界模型和政策，可以由RL代理利用。我们提供一系列示例RLANG程序，并演示不同的RL方法如何利用所得的知识，包括无模型和基于模型的表格算法，分层方法和深度RL算法（包括策略梯度和基于价值的方法）。

最近，深增强学习（DRL）方法在各种域中的任务方面取得了令人印象深刻的性能。然而，用DRL方法产生的神经网络政策不是人为可解释的，并且通常难以推广到新颖的情景。为了解决这些问题，事先作品探索学习更具可诠释和构建的概括的程序政策。然而，这些作品要么采用有限的政策表示（例如，决策树，状态机或预定义的程序模板）或需要更强的监督（例如输入/输出状态对或专家演示）。我们提出了一个框架，而是学习合成一个程序，该程序详细介绍了以灵活和表现力的方式解决任务的过程，仅来自奖励信号。为了减轻学习难以从头开始诱发所需的代理行为的难度，我们建议首先了解一个程序嵌入空间，以不传达的方式连续参加各种行为，然后搜索嵌入空间以产生程序最大化给定任务的返回。实验结果表明，所提出的框架不仅可以可靠地综合任务解决方案，而且在产生可解释和更广泛的政策的同时优于DRL和程序合成基线。我们还可以证明所提出的两级学习计划的必要性，并分析了学习计划嵌入的各种方法。

Reinforcement Learning (RL) is a popular machine learning paradigm where intelligent agents interact with the environment to fulfill a long-term goal. Driven by the resurgence of deep learning, Deep RL (DRL) has witnessed great success over a wide spectrum of complex control tasks. Despite the encouraging results achieved, the deep neural network-based backbone is widely deemed as a black box that impedes practitioners to trust and employ trained agents in realistic scenarios where high security and reliability are essential. To alleviate this issue, a large volume of literature devoted to shedding light on the inner workings of the intelligent agents has been proposed, by constructing intrinsic interpretability or post-hoc explainability. In this survey, we provide a comprehensive review of existing works on eXplainable RL (XRL) and introduce a new taxonomy where prior works are clearly categorized into model-explaining, reward-explaining, state-explaining, and task-explaining methods. We also review and highlight RL methods that conversely leverage human knowledge to promote learning efficiency and performance of agents while this kind of method is often ignored in XRL field. Some challenges and opportunities in XRL are discussed. This survey intends to provide a high-level summarization of XRL and to motivate future research on more effective XRL solutions. Corresponding open source codes are collected and categorized at https://github.com/Plankson/awesome-explainable-reinforcement-learning.

Recently, some challenging tasks in multi-agent systems have been solved by some hierarchical reinforcement learning methods. Inspired by the intra-level and inter-level coordination in the human nervous system, we propose a novel value decomposition framework HAVEN based on hierarchical reinforcement learning for fully cooperative multi-agent problems. To address the instability arising from the concurrent optimization of policies between various levels and agents, we introduce the dual coordination mechanism of inter-level and inter-agent strategies by designing reward functions in a two-level hierarchy. HAVEN does not require domain knowledge and pre-training, and can be applied to any value decomposition variant. Our method achieves desirable results on different decentralized partially observable Markov decision process domains and outperforms other popular multi-agent hierarchical reinforcement learning algorithms.

尽管近年来在多机构增强学习（MARL）方面取得了重大进展，但复杂领域的协调仍然是一个挑战。 MARL的工作通常专注于解决代理与环境中所有其他代理和实体互动的任务；但是，我们观察到现实世界任务通常由几个局部代理相互作用（子任务）的几个隔离实例组成，并且每个代理都可以有意义地专注于一个子任务，以排除环境中其他所有内容。在这些综合任务中，成功的策略通常可以分解为两个决策级别：代理人分配给特定的子任务，并且每个代理人仅针对其指定的子任务有效地采取行动。这种分解的决策提供了强烈的结构感应偏见，大大降低了代理观察空间，并鼓励在训练期间重复使用和组成子任务特异性策略，而不是将子任务的每个新组成视为独特的。我们介绍了ALMA，这是一种利用这些结构化任务的一般学习方法。阿尔玛同时学习高级子任务分配策略和低级代理政策。我们证明，阿尔玛（Alma）在许多具有挑战性的环境中学习了复杂的协调行为，表现优于强大的基准。 Alma的模块化还使其能够更好地概括为新的环境配置。最后，我们发现，尽管ALMA可以整合受过训练的分配和行动策略，但最佳性能仅通过共同训练所有组件才能获得。我们的代码可从https://github.com/shariqiqbal2810/alma获得

许多现实世界的应用程序都可以作为多机构合作问题进行配置，例如网络数据包路由和自动驾驶汽车的协调。深入增强学习（DRL）的出现为通过代理和环境的相互作用提供了一种有前途的多代理合作方法。但是，在政策搜索过程中，传统的DRL解决方案遭受了多个代理具有连续动作空间的高维度。此外，代理商政策的动态性使训练非平稳。为了解决这些问题，我们建议采用高级决策和低水平的个人控制，以进行有效的政策搜索，提出一种分层增强学习方法。特别是，可以在高级离散的动作空间中有效地学习多个代理的合作。同时，低水平的个人控制可以减少为单格强化学习。除了分层增强学习外，我们还建议对手建模网络在学习过程中对其他代理的政策进行建模。与端到端的DRL方法相反，我们的方法通过以层次结构将整体任务分解为子任务来降低学习的复杂性。为了评估我们的方法的效率，我们在合作车道变更方案中进行了现实世界中的案例研究。模拟和现实世界实验都表明我们的方法在碰撞速度和收敛速度中的优越性。

学习协作对于多机构增强学习（MARL）至关重要。以前的作品通过最大化代理行为的相关性来促进协作，该行为的相关性通常以不同形式的相互信息（MI）为特征。但是，我们揭示了次最佳的协作行为，也出现了强烈的相关性，并且简单地最大化MI可以阻碍学习的学习能力。为了解决这个问题，我们提出了一个新颖的MARL框架，称为“渐进式信息协作（PMIC）”，以进行更有效的MI驱动协作。 PMIC使用全球国家和联合行动之间MI测量的新协作标准。基于此标准，PMIC的关键思想是最大程度地提高与优越的协作行为相关的MI，并最大程度地减少与下等方面相关的MI。这两个MI目标通过促进更好的合作，同时避免陷入次级优势，从而扮演互补的角色。与其他算法相比，在各种MARL基准测试的实验表明，PMIC的表现出色。

Cooperative multi-agent reinforcement learning (MARL) has achieved significant results, most notably by leveraging the representation-learning abilities of deep neural networks. However, large centralized approaches quickly become infeasible as the number of agents scale, and fully decentralized approaches can miss important opportunities for information sharing and coordination. Furthermore, not all agents are equal -- in some cases, individual agents may not even have the ability to send communication to other agents or explicitly model other agents. This paper considers the case where there is a single, powerful, \emph{central agent} that can observe the entire observation space, and there are multiple, low-powered \emph{local agents} that can only receive local observations and are not able to communicate with each other. The central agent's job is to learn what message needs to be sent to different local agents based on the global observations, not by centrally solving the entire problem and sending action commands, but by determining what additional information an individual agent should receive so that it can make a better decision. In this work we present our MARL algorithm \algo, describe where it would be most applicable, and implement it in the cooperative navigation and multi-agent walker domains. Empirical results show that 1) learned communication does indeed improve system performance, 2) results generalize to heterogeneous local agents, and 3) results generalize to different reward structures.

在现实设置中跨多个代理的决策同步是有问题的，因为它要求代理等待其他代理人终止和交流有关终止的终止。理想情况下，代理应该学习和执行异步。这样的异步方法还允许暂时扩展的动作，这些操作可能会根据执行的情况和操作花费不同的时间。不幸的是，当前的策略梯度方法不适用于异步设置，因为他们认为代理在每个时间步骤中都同步推理了动作选择。为了允许异步学习和决策，我们制定了一组异步的多代理参与者 - 批判性方法，这些方法使代理可以在三个标准培训范式中直接优化异步策略：分散的学习，集中学习，集中学习和集中培训以进行分解执行。各种现实域中的经验结果（在模拟和硬件中）证明了我们在大型多代理问题中的优势，并验证了我们算法在学习高质量和异步解决方案方面的有效性。

本文考虑了多智能经纪人强化学习（MARL）任务，代理商在集会结束时获得共享全球奖励。这种奖励的延迟性质影响了代理商在中间时间步骤中评估其行动质量的能力。本文侧重于开发学习焦点奖励的时间重新分布的方法，以获得密集奖励信号。解决这些MARL问题需要解决两个挑战：识别（1）沿着集发作（沿时间）的长度相对重要性，以及（2）在任何单一时间步骤（代理商中）的相对重要性。在本文中，我们介绍了奖励中的奖励再分配，在整容多智能体加固学习（Arel）中奖励再分配，以解决这两个挑战。 Arel使用注意机制来表征沿着轨迹（时间关注）对状态转换的动作的影响，以及每个代理在每个时间步骤（代理人注意）的影响。 Arel预测的重新分配奖励是密集的，可以与任何给定的MARL算法集成。我们评估了粒子世界环境的具有挑战性的任务和星际争霸多功能挑战。 arel导致粒子世界的奖励较高，并改善星际争端的胜利率与三个最先进的奖励再分配方法相比。我们的代码可在https://github.com/baicenxiao/arel获得。

我们开发了一个多功能辅助救援学习（MARL）方法，以了解目标跟踪的可扩展控制策略。我们的方法可以处理任意数量的追求者和目标;我们显示出现的任务，该任务包括高达1000追踪跟踪1000个目标。我们使用分散的部分可观察的马尔可夫决策过程框架来模拟追求者作为接受偏见观察（范围和轴承）的代理，了解使用固定的未知政策的目标。注意机制用于参数化代理的价值函数;这种机制允许我们处理任意数量的目标。熵 - 正规的脱助政策RL方法用于培训随机政策，我们讨论如何在追求者之间实现对冲行为，尽管有完全分散的控制执行，但仍然导致合作较弱的合作形式。我们进一步开发了一个掩蔽启发式，允许训练较少的问题，少量追求目标和在更大的问题上执行。进行彻底的仿真实验，消融研究和对现有技术算法的比较，以研究对不同数量的代理和目标性能的方法和鲁棒性的可扩展性。

强化学习的关键挑战是解决了长地平规划问题。最近的工作已经利用计划在这些设置中引导钢筋学习。但是，这些方法对用户施加了高手动负担，因为它们必须为每项新任务提供指导计划。部分观察到的环境进一步使编程任务复杂化，因为程序必须实现正确，理想地最佳地实现策略，处理环境的隐藏区域的所有可能配置。我们提出了一种新的方法，模型预测程序合成（MPP），它使用程序综合来自动生成指导程序。它培训了一种生成模型来预测世界的未观察到的部分，然后以鲁棒到其不确定性的方式基于来自该模型的样本来综合程序。在我们的实验中，我们表明我们的方法在一组具有挑战性的基准上显着优于非程序引导的方法，包括2D Minecraft-Inspired环境，代理商必须完成复杂的子组织序列来实现其目标，并实现类似的使用手动程序指导代理的性能。我们的结果表明，我们的方法可以在不需要用户为每项新任务提供新的指导计划的情况下获得方案引导的强化学习的好处。

大型语言模型可以编码有关世界的大量语义知识。这种知识对于旨在采取自然语言表达的高级，时间扩展的指示的机器人可能非常有用。但是，语言模型的一个重大弱点是，它们缺乏现实世界的经验，这使得很难利用它们在给定的体现中进行决策。例如，要求语言模型描述如何清洁溢出物可能会导致合理的叙述，但是它可能不适用于需要在特定环境中执行此任务的特定代理商（例如机器人）。我们建议通过预处理的技能来提供现实世界的基础，这些技能用于限制模型以提出可行且在上下文上适当的自然语言动作。机器人可以充当语​​言模型的“手和眼睛”，而语言模型可以提供有关任务的高级语义知识。我们展示了如何将低级技能与大语言模型结合在一起，以便语言模型提供有关执行复杂和时间扩展说明的过程的高级知识，而与这些技能相关的价值功能则提供了连接必要的基础了解特定的物理环境。我们在许多现实世界的机器人任务上评估了我们的方法，我们表明了对现实世界接地的需求，并且这种方法能够在移动操纵器上完成长远，抽象的自然语言指令。该项目的网站和视频可以在https://say-can.github.io/上找到。

With the development of deep representation learning, the domain of reinforcement learning (RL) has become a powerful learning framework now capable of learning complex policies in high dimensional environments. This review summarises deep reinforcement learning (DRL) algorithms and provides a taxonomy of automated driving tasks where (D)RL methods have been employed, while addressing key computational challenges in real world deployment of autonomous driving agents. It also delineates adjacent domains such as behavior cloning, imitation learning, inverse reinforcement learning that are related but are not classical RL algorithms. The role of simulators in training agents, methods to validate, test and robustify existing solutions in RL are discussed.

Cooperative multi-agent reinforcement learning (MARL) has made prominent progress in recent years. For training efficiency and scalability, most of the MARL algorithms make all agents share the same policy or value network. However, in many complex multi-agent tasks, different agents are expected to possess specific abilities to handle different subtasks. In those scenarios, sharing parameters indiscriminately may lead to similar behavior across all agents, which will limit the exploration efficiency and degrade the final performance. To balance the training complexity and the diversity of agent behavior, we propose a novel framework to learn dynamic subtask assignment (LDSA) in cooperative MARL. Specifically, we first introduce a subtask encoder to construct a vector representation for each subtask according to its identity. To reasonably assign agents to different subtasks, we propose an ability-based subtask selection strategy, which can dynamically group agents with similar abilities into the same subtask. In this way, agents dealing with the same subtask share their learning of specific abilities and different subtasks correspond to different specific abilities. We further introduce two regularizers to increase the representation difference between subtasks and stabilize the training by discouraging agents from frequently changing subtasks, respectively. Empirical results show that LDSA learns reasonable and effective subtask assignment for better collaboration and significantly improves the learning performance on the challenging StarCraft II micromanagement benchmark and Google Research Football.

深度强化学习（DRL）和深度多机构的强化学习（MARL）在包括游戏AI，自动驾驶汽车，机器人技术等各种领域取得了巨大的成功。但是，众所周知，DRL和Deep MARL代理的样本效率低下，即使对于相对简单的问题设置，通常也需要数百万个相互作用，从而阻止了在实地场景中的广泛应用和部署。背后的一个瓶颈挑战是众所周知的探索问题，即如何有效地探索环境和收集信息丰富的经验，从而使政策学习受益于最佳研究。在稀疏的奖励，吵闹的干扰，长距离和非平稳的共同学习者的复杂环境中，这个问题变得更加具有挑战性。在本文中，我们对单格和多代理RL的现有勘探方法进行了全面的调查。我们通过确定有效探索的几个关键挑战开始调查。除了上述两个主要分支外，我们还包括其他具有不同思想和技术的著名探索方法。除了算法分析外，我们还对一组常用基准的DRL进行了全面和统一的经验比较。根据我们的算法和实证研究，我们终于总结了DRL和Deep Marl中探索的公开问题，并指出了一些未来的方向。