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.

Reinforcement learning in multi-agent scenarios is important for real-world applications but presents challenges beyond those seen in singleagent settings. We present an actor-critic algorithm that trains decentralized policies in multiagent settings, using centrally computed critics that share an attention mechanism which selects relevant information for each agent at every timestep. This attention mechanism enables more effective and scalable learning in complex multiagent environments, when compared to recent approaches. Our approach is applicable not only to cooperative settings with shared rewards, but also individualized reward settings, including adversarial settings, as well as settings that do not provide global states, and it makes no assumptions about the action spaces of the agents. As such, it is flexible enough to be applied to most multi-agent learning problems.

This work considers the problem of learning cooperative policies in complex, partially observable domains without explicit communication. We extend three classes of single-agent deep reinforcement learning algorithms based on policy gradient, temporal-difference error, and actor-critic methods to cooperative multi-agent systems. We introduce a set of cooperative control tasks that includes tasks with discrete and continuous actions, as well as tasks that involve hundreds of agents. The three approaches are evaluated against each other using different neural architectures, training procedures, and reward structures. Using deep reinforcement learning with a curriculum learning scheme, our approach can solve problems that were previously considered intractable by most multi-agent reinforcement learning algorithms. We show that policy gradient methods tend to outperform both temporal-difference and actor-critic methods when using feed-forward neural architectures. We also show that recurrent policies, while more difficult to train, outperform feed-forward policies on our evaluation tasks.

独立的强化学习算法没有理论保证，用于在多代理设置中找到最佳策略。然而，在实践中，先前的作品报告了在某些域中的独立算法和其他方面的良好性能。此外，文献中缺乏对独立算法的优势和弱点的全面研究。在本文中，我们对四个Pettingzoo环境进行了独立算法的性能的实证比较，这些环境跨越了三种主要类别的多助理环境，即合作，竞争和混合。我们表明，在完全可观察的环境中，独立的算法可以在协作和竞争环境中与多代理算法进行同步。对于混合环境，我们表明通过独立算法培训的代理商学会单独执行，但未能学会与盟友合作并与敌人竞争。我们还表明，添加重复性提高了合作部分可观察环境中独立算法的学习。

We explore deep reinforcement learning methods for multi-agent domains. We begin by analyzing the difficulty of traditional algorithms in the multi-agent case: Q-learning is challenged by an inherent non-stationarity of the environment, while policy gradient suffers from a variance that increases as the number of agents grows. We then present an adaptation of actor-critic methods that considers action policies of other agents and is able to successfully learn policies that require complex multiagent coordination. Additionally, we introduce a training regimen utilizing an ensemble of policies for each agent that leads to more robust multi-agent policies. We show the strength of our approach compared to existing methods in cooperative as well as competitive scenarios, where agent populations are able to discover various physical and informational coordination strategies.

多代理深入的强化学习已应用于解决各种离散或连续动作空间的各种复杂问题，并取得了巨大的成功。但是，大多数实际环境不能仅通过离散的动作空间或连续的动作空间来描述。而且很少有作品曾经利用深入的加固学习（DRL）来解决混合动作空间的多代理问题。因此，我们提出了一种新颖的算法：深层混合软性角色 - 批评（MAHSAC）来填补这一空白。该算法遵循集中式训练但分散执行（CTDE）范式，并扩展软actor-Critic算法（SAC），以根据最大熵在多机构环境中处理混合动作空间问题。我们的经验在一个简单的多代理粒子世界上运行，具有连续的观察和离散的动作空间以及一些基本的模拟物理。实验结果表明，MAHSAC在训练速度，稳定性和抗干扰能力方面具有良好的性能。同时，它在合作场景和竞争性场景中胜过现有的独立深层学习方法。

流动性和流量的许多方案都涉及多种不同的代理，需要合作以找到共同解决方案。行为计划的最新进展使用强化学习以寻找有效和绩效行为策略。但是，随着自动驾驶汽车和车辆对X通信变得越来越成熟，只有使用单身独立代理的解决方案在道路上留下了潜在的性能增长。多代理增强学习（MARL）是一个研究领域，旨在为彼此相互作用的多种代理找到最佳解决方案。这项工作旨在将该领域的概述介绍给研究人员的自主行动能力。我们首先解释Marl并介绍重要的概念。然后，我们讨论基于Marl算法的主要范式，并概述每个范式中最先进的方法和思想。在这种背景下，我们调查了MAL在自动移动性场景中的应用程序，并概述了现有的场景和实现。

在人工多智能体系中，学习协作政策的能力是基于代理商的沟通技巧，他们必须能够编码从环境中收到的信息，并学习如何与手头任务所要求的其他代理分享它。我们介绍了一个深度加强学习方法，连接驱动的通信（CDC），促进了多种子体协作行为的出现，仅通过经验。代理被建模为加权图的节点，其状态相关的边缘编码可以交换的对方式。我们介绍了一种依赖于图形的关注机制，可以控制代理的传入消息如何加权。此机制完全核对图表所表示的系统的当前状态，并在捕获信息如何在图中流动的扩散过程中构建。图形拓扑未被假定已知先验，但在代理人的观察中动态依赖于代理人，并以端到端的方式与注意机制和政策同时学习。我们的经验结果表明，CDC能够学习有效的协作政策，并可以在合作导航任务上过度执行竞争学习算法。

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。

政策梯度方法在多智能体增强学习中变得流行，但由于存在环境随机性和探索代理（即非公平性​​），它们遭受了高度的差异，这可能因信用分配难度而受到困扰。结果，需要一种方法，该方法不仅能够有效地解决上述两个问题，而且需要足够强大地解决各种任务。为此，我们提出了一种新的多代理政策梯度方法，称为强大的本地优势（ROLA）演员 - 评论家。 Rola允许每个代理人将个人动作值函数作为当地评论家，以及通过基于集中评论家的新型集中培训方法来改善环境不良。通过使用此本地批评，每个代理都计算基准，以减少对其策略梯度估计的差异，这导致含有其他代理的预期优势动作值，这些选项可以隐式提高信用分配。我们在各种基准测试中评估ROLA，并在许多最先进的多代理政策梯度算法上显示其鲁棒性和有效性。

将深度强化学习（DRL）扩展到多代理领域的研究已经解决了许多复杂的问题，并取得了重大成就。但是，几乎所有这些研究都只关注离散或连续的动作空间，而且很少有作品曾经使用过多代理的深度强化学习来实现现实世界中的环境问题，这些问题主要具有混合动作空间。因此，在本文中，我们提出了两种算法：深层混合软性角色批评（MAHSAC）和多代理混合杂种深层确定性政策梯度（MAHDDPG）来填补这一空白。这两种算法遵循集中式培训和分散执行（CTDE）范式，并可以解决混合动作空间问题。我们的经验在多代理粒子环境上运行，这是一个简单的多代理粒子世界，以及一些基本的模拟物理。实验结果表明，这些算法具有良好的性能。

We consider the problem of multiple agents sensing and acting in environments with the goal of maximising their shared utility. In these environments, agents must learn communication protocols in order to share information that is needed to solve the tasks. By embracing deep neural networks, we are able to demonstrate endto-end learning of protocols in complex environments inspired by communication riddles and multi-agent computer vision problems with partial observability. We propose two approaches for learning in these domains: Reinforced Inter-Agent Learning (RIAL) and Differentiable Inter-Agent Learning (DIAL). The former uses deep Q-learning, while the latter exploits the fact that, during learning, agents can backpropagate error derivatives through (noisy) communication channels. Hence, this approach uses centralised learning but decentralised execution. Our experiments introduce new environments for studying the learning of communication protocols and present a set of engineering innovations that are essential for success in these domains.

多代理深度增强学习（Marl）缺乏缺乏共同使用的评估任务和标准，使方法之间的比较困难。在这项工作中，我们提供了一个系统评估，并比较了三种不同类别的Marl算法（独立学习，集中式多代理政策梯度，价值分解）在各种协作多智能经纪人学习任务中。我们的实验是在不同学习任务中作为算法的预期性能的参考，我们为不同学习方法的有效性提供了见解。我们开源EPYMARL，它将Pymarl CodeBase扩展到包括其他算法，并允许灵活地配置算法实现细节，例如参数共享。最后，我们开源两种环境，用于多智能经纪研究，重点关注稀疏奖励下的协调。

Many real-world problems, such as network packet routing and the coordination of autonomous vehicles, are naturally modelled as cooperative multi-agent systems. There is a great need for new reinforcement learning methods that can efficiently learn decentralised policies for such systems. To this end, we propose a new multi-agent actor-critic method called counterfactual multi-agent (COMA) policy gradients. COMA uses a centralised critic to estimate the Q-function and decentralised actors to optimise the agents' policies. In addition, to address the challenges of multi-agent credit assignment, it uses a counterfactual baseline that marginalises out a single agent's action, while keeping the other agents' actions fixed. COMA also uses a critic representation that allows the counterfactual baseline to be computed efficiently in a single forward pass. We evaluate COMA in the testbed of StarCraft unit micromanagement, using a decentralised variant with significant partial observability. COMA significantly improves average performance over other multi-agent actorcritic methods in this setting, and the best performing agents are competitive with state-of-the-art centralised controllers that get access to the full state.

在合作多智能体增强学习（Marl）中的代理商的创造和破坏是一个批判性的研究领域。当前的Marl算法通常认为，在整个实验中，组内的代理数量仍然是固定的。但是，在许多实际问题中，代理人可以在队友之前终止。这次早期终止问题呈现出挑战：终止的代理人必须从本集团的成功或失败中学习，这是超出其自身存在的成败。我们指代薪资奖励的传播价值作为遣返代理商作为追索的奖励作为追索权。当前的MARL方法通过将这些药剂放在吸收状态下，直到整组试剂达到终止条件，通过将这些药剂置于终止状态来处理该问题。虽然吸收状态使现有的算法和API能够在没有修改的情况下处理终止的代理，但存在实际培训效率和资源使用问题。在这项工作中，我们首先表明样本复杂性随着系统监督学习任务中的吸收状态的数量而增加，同时对变量尺寸输入更加强大。然后，我们为现有的最先进的MARL算法提出了一种新颖的架构，它使用注意而不是具有吸收状态的完全连接的层。最后，我们展示了这一新颖架构在剧集中创建或销毁的任务中的标准架构显着优于标准架构以及标准的多代理协调任务。

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。

Modern multi-agent reinforcement learning frameworks rely on centralized training and reward shaping to perform well. However, centralized training and dense rewards are not readily available in the real world. Current multi-agent algorithms struggle to learn in the alternative setup of decentralized training or sparse rewards. To address these issues, we propose a self-supervised intrinsic reward ELIGN - expectation alignment - inspired by the self-organization principle in Zoology. Similar to how animals collaborate in a decentralized manner with those in their vicinity, agents trained with expectation alignment learn behaviors that match their neighbors' expectations. This allows the agents to learn collaborative behaviors without any external reward or centralized training. We demonstrate the efficacy of our approach across 6 tasks in the multi-agent particle and the complex Google Research football environments, comparing ELIGN to sparse and curiosity-based intrinsic rewards. When the number of agents increases, ELIGN scales well in all multi-agent tasks except for one where agents have different capabilities. We show that agent coordination improves through expectation alignment because agents learn to divide tasks amongst themselves, break coordination symmetries, and confuse adversaries. These results identify tasks where expectation alignment is a more useful strategy than curiosity-driven exploration for multi-agent coordination, enabling agents to do zero-shot coordination.

几乎所有的多代理强化学习算法没有交流，都遵循分散执行的集中培训原则。在集中培训期间，代理可以以相同的信号为指导，例如全球国家。但是，在分散执行期间，代理缺乏共享信号。受到观点不变性和对比学习的启发，我们在本文中提出了共识学习，以学习合作的多代理增强学习。尽管基于局部观察结果，但不同的代理可以在离散空间中推断出相同的共识。在分散执行期间，我们将推断的共识作为对代理网络的明确输入提供了，从而发展了他们的合作精神。我们提出的方法可以扩展到具有小模型更改的各种多代理增强学习算法。此外，我们执行一些完全合作的任务，并获得令人信服的结果。

Communication is supposed to improve multi-agent collaboration and overall performance in cooperative Multi-agent reinforcement learning (MARL). However, such improvements are prevalently limited in practice since most existing communication schemes ignore communication overheads (e.g., communication delays). In this paper, we demonstrate that ignoring communication delays has detrimental effects on collaborations, especially in delay-sensitive tasks such as autonomous driving. To mitigate this impact, we design a delay-aware multi-agent communication model (DACOM) to adapt communication to delays. Specifically, DACOM introduces a component, TimeNet, that is responsible for adjusting the waiting time of an agent to receive messages from other agents such that the uncertainty associated with delay can be addressed. Our experiments reveal that DACOM has a non-negligible performance improvement over other mechanisms by making a better trade-off between the benefits of communication and the costs of waiting for messages.

We consider the problem of multi-agent navigation and collision avoidance when observations are limited to the local neighborhood of each agent. We propose InforMARL, a novel architecture for multi-agent reinforcement learning (MARL) which uses local information intelligently to compute paths for all the agents in a decentralized manner. Specifically, InforMARL aggregates information about the local neighborhood of agents for both the actor and the critic using a graph neural network and can be used in conjunction with any standard MARL algorithm. We show that (1) in training, InforMARL has better sample efficiency and performance than baseline approaches, despite using less information, and (2) in testing, it scales well to environments with arbitrary numbers of agents and obstacles.