Decentralized bilevel optimization has received increasing attention recently due to its foundational role in many emerging multi-agent learning paradigms (e.g., multi-agent meta-learning and multi-agent reinforcement learning) over peer-to-peer edge networks. However, to work with the limited computation and communication capabilities of edge networks, a major challenge in developing decentralized bilevel optimization techniques is to lower sample and communication complexities. This motivates us to develop a new decentralized bilevel optimization called DIAMOND (decentralized single-timescale stochastic approximation with momentum and gradient-tracking). The contributions of this paper are as follows: i) our DIAMOND algorithm adopts a single-loop structure rather than following the natural double-loop structure of bilevel optimization, which offers low computation and implementation complexity; ii) compared to existing approaches, the DIAMOND algorithm does not require any full gradient evaluations, which further reduces both sample and computational complexities; iii) through a careful integration of momentum information and gradient tracking techniques, we show that the DIAMOND algorithm enjoys $\mathcal{O}(\epsilon^{-3/2})$ in sample and communication complexities for achieving an $\epsilon$-stationary solution, both of which are independent of the dataset sizes and significantly outperform existing works. Extensive experiments also verify our theoretical findings.
translated by 谷歌翻译
我们研究了受限的强化学习问题,其中代理的目的是最大程度地提高预期的累积奖励,从而受到对实用程序函数的预期总价值的约束。与现有的基于模型的方法或无模型方法伴随着“模拟器”,我们旨在开发第一个无模型的无模拟算法,即使在大规模系统中,也能够实现sublinear遗憾和透明度的约束侵犯。为此,我们考虑具有线性函数近似的情节约束决策过程,其中过渡动力学和奖励函数可以表示为某些已知功能映射的线性函数。我们表明$ \ tilde {\ mathcal {o}}(\ sqrt {d^3h^3t})$遗憾和$ \ tilde {\ tillcal {\ mathcal {o}}(\ sqrt {d^3h^3ht})$约束$约束$约束可以实现违规范围,其中$ d $是功能映射的尺寸,$ h $是情节的长度,而$ t $是总数的总数。我们的界限是在没有明确估计未知过渡模型或需要模拟器的情况下达到的,并且仅通过特征映射的维度依赖于状态空间。因此,即使国家的数量进入无穷大,我们的界限也会存在。我们的主要结果是通过标准LSVI-UCB算法的新型适应来实现的。特别是,我们首先将原始二次优化引入LSVI-UCB算法中,以在遗憾和违反约束之间取得平衡。更重要的是,我们使用软马克斯政策取代了LSVI-UCB中的状态行动功能的标准贪婪选择。事实证明,这对于通过其近似平滑度的权衡来确定受约束案例的统一浓度是关键。我们还表明,一个人可以达到均匀的约束违规行为,同时仍然保持相同的订单相对于$ t $。
translated by 谷歌翻译
我们考虑在马尔可夫决策过程中的强化学习(RL),其中代理人反复交互与由受控马尔可夫进程建模的环境进行交互。在每次步骤$ $ $时,它赢得了奖励,并招收了由$ M $成本组成的成本矢量。我们设计学习算法,最大限度地提高$ T $时间步长的时间范围内获得的累积奖励,同时确保$ M $成本支出的平均值由代理指定的阈值界限为$ C ^ {UB} _I ,i = 1,2,\ ldots,m $。关于累积成本支出的审议从现有文献中离开,因为代理商此外需要以在线方式平衡成本费用,同时执行通常遇到的RL任务中的勘探开发权衡。为了测量满足平均成本约束的加强学习算法的性能,我们定义了由其奖励后悔组成的$ M + 1 $维度遗憾的载体,而M $费用遗憾。奖励后悔在累计奖励中衡量次级最优性,而成本遗憾的奖励奖励奖励是其$ I $ -Th累计成本费用与预期成本支出之间的差异,而预期的成本支出$ TC ^ {UB} _i $。我们证明,通过高概率,UCRL-CMDP的遗憾矢量是高度限制的(S \ SQRT {AT ^ {1.5} \ log(t)\右)$,其中$ s $状态的数量,$ a $是行动的数量,而$ t $是时间范围。我们进一步展示了如何减少预期奖金的所需子集的遗憾,以牺牲奖励遗憾和剩余成本的牺牲品为代价。据我们所知,我们的是唯一考虑在平均成本限制下的非焦化RL的工作,并且可以根据代理人对其成本遗憾的要求进行〜\ excph {调整后悔向量}的算法。
translated by 谷歌翻译
Deep neural networks (DNN) are prone to miscalibrated predictions, often exhibiting a mismatch between the predicted output and the associated confidence scores. Contemporary model calibration techniques mitigate the problem of overconfident predictions by pushing down the confidence of the winning class while increasing the confidence of the remaining classes across all test samples. However, from a deployment perspective, an ideal model is desired to (i) generate well-calibrated predictions for high-confidence samples with predicted probability say >0.95, and (ii) generate a higher proportion of legitimate high-confidence samples. To this end, we propose a novel regularization technique that can be used with classification losses, leading to state-of-the-art calibrated predictions at test time; From a deployment standpoint in safety-critical applications, only high-confidence samples from a well-calibrated model are of interest, as the remaining samples have to undergo manual inspection. Predictive confidence reduction of these potentially ``high-confidence samples'' is a downside of existing calibration approaches. We mitigate this by proposing a dynamic train-time data pruning strategy that prunes low-confidence samples every few epochs, providing an increase in "confident yet calibrated samples". We demonstrate state-of-the-art calibration performance across image classification benchmarks, reducing training time without much compromise in accuracy. We provide insights into why our dynamic pruning strategy that prunes low-confidence training samples leads to an increase in high-confidence samples at test time.
translated by 谷歌翻译
We are interested in neurosymbolic systems consisting of a high-level symbolic layer for explainable prediction in terms of human-intelligible concepts; and a low-level neural layer for extracting symbols required to generate the symbolic explanation. Real data is often imperfect meaning that even if the symbolic theory remains unchanged, we may still need to address the problem of mapping raw data to high-level symbols, each time there is a change in the data acquisition environment or equipment. Manual (re-)annotation of the raw data each time this happens is laborious and expensive; and automated labelling methods are often imperfect, especially for complex problems. NEUROLOG proposed the use of a semantic loss function that allows an existing feature-based symbolic model to guide the extraction of feature-values from raw data, using `abduction'. However, the experiments demonstrating the use of semantic loss through abduction appear to rely heavily on a domain-specific pre-processing step that enables a prior delineation of feature locations in the raw data. We examine the use of semantic loss in domains where such pre-processing is not possible, or is not obvious. We show that without any prior information about the features, the NEUROLOG approach can continue to predict accurately even with substantially incorrect feature predictions. We show also that prior information about the features in the form of even imperfect pre-training can help correct this situation. These findings are replicated on the original problem considered by NEUROLOG, without the use of feature-delineation. This suggests that symbolic explanations constructed for data in a domain could be re-used in a related domain, by `feature-adaptation' of pre-trained neural extractors using the semantic loss function constrained by abductive feedback.
translated by 谷歌翻译
类比推理问题挑战了连接主义者和符号AI系统,因为这些系统需要将背景知识,推理和模式识别的结合。符号系统摄入显式域知识并执行演绎推理,但它们对噪声敏感,并且需要输入以预设符号特征。另一方面,Connectionist系统可以直接摄入丰富的输入空间,例如图像,文本或语音,即使使用嘈杂的输入也可以识别模式。但是,Connectionist模型努力将明确的领域知识用于演绎推理。在本文中,我们提出了一个框架,将神经网络的模式识别能力与象征性推理和背景知识结合在一起,以解决一类类似推理问题,其中一组属性和可能的​​关系是已知的。我们从“神经算法推理”方法[DeepMind 2020]中汲取灵感,并通过(i)基于问题的象征模型学习分布式表示(ii)培训神经网络转化反映了关系的分布式表示形式。参与问题,最后(iii)培训神经网络编码器,从图像到(i)中的分布式表示。这三个要素使我们能够使用神经网络作为操纵分布式表示的基本功能执行基于搜索的推理。我们在乌鸦渐进式矩阵中的视觉类比问题上进行了测试,并在人类绩效中实现准确性竞争,在某些情况下,优于初始端到端神经网络方法的方法。尽管最近接受大规模训练的神经模型产生了SOTA,但我们的新型神经符号推理方法是该问题的有希望的方向,可以说是更笼统的,尤其是对于可用的域知识的问题。
translated by 谷歌翻译
线虫秀丽隐杆线虫(秀丽隐杆线虫)被用作模型生物体,以更好地了解发育生物学和神经生物学。秀丽隐杆线虫具有不变的细胞谱系,已使用荧光显微镜图像进行了分类和观察。然而,一旦开始零星的肌肉抽搐,已建立的跟踪细胞的方法就无法概括。我们以方法为基础,该方法将皮肤细胞用作基准标记,尽管随机抽搐,但仍在进行细胞跟踪。特别是,我们提出了一个细胞核分割和跟踪程序,该过程被整合到3D渲染GUI中,以提高在晚期发育过程中跟踪细胞的效率。在三个测试胚胎上描述上述肌肉细胞核的图像上的结果表明,基准标记与经典的跟踪范式结合使用,克服了零星的抽搐。
translated by 谷歌翻译
最近的工作突出了因果关系在设计公平决策算法中的作用。但是,尚不清楚现有的公平因果概念如何相互关系,或者将这些定义作为设计原则的后果是什么。在这里,我们首先将算法公平性的流行因果定义组装成两个广泛的家庭:(1)那些限制决策对反事实差异的影响的家庭; (2)那些限制了法律保护特征(如种族和性别)对决策的影响。然后,我们在分析和经验上表明,两个定义的家庭\ emph {几乎总是总是} - 从一种理论意义上讲 - 导致帕累托占主导地位的决策政策,这意味着每个利益相关者都有一个偏爱的替代性,不受限制的政策从大型自然级别中绘制。例如,在大学录取决定的情况下,每位利益相关者都不支持任何对学术准备和多样性的中立或积极偏好的利益相关者,将不利于因果公平定义的政策。的确,在因果公平的明显定义下,我们证明了由此产生的政策要求承认所有具有相同概率的学生,无论学术资格或小组成员身份如何。我们的结果突出了正式的局限性和因果公平的常见数学观念的潜在不利后果。
translated by 谷歌翻译
我们考虑一类视觉模拟推理问题,涉及发现输入/输出图像对相关的转换序列,以类似地改变未来输入。该程序综合任务可以通过符号搜索轻松解决。使用(Velickovic和Blundell 2021)的“神经模拟推理”方法的变化,Edw,例如,搜索一系列基本神经网络变换,其操纵从符号空间导出的分布式表示,输入图像直接编码。我们评估了我们的“神经原理”方法对具有看不见形状和位置的图像的程度。
translated by 谷歌翻译
流量交叉点的机芯特定车辆分类和计数是各种交通管理活动的重要组成部分。在这种情况下,在最近基于计算机视觉的技术方面的进步,相机已经成为从交通场景中提取车辆轨迹的可靠数据源。然而,随着这种方式的运动轨迹的特性根据相机校准而变化,对这些轨迹进行分类非常具有挑战性。虽然一些现有方法已经解决了具有体面准确性的此类分类任务,但这些方法的性能显着依赖于手动规范的几个感兴趣区域。在这项研究中,我们提出了一种自动分类方法,用于移动基于Vision的车辆轨迹的特定分类(例如右转,左转和通过运动)。我们的分类框架使用此后,采用基于同性的分配策略来指定在交通场景中观察到的不同运动模式,以将传入的车辆轨迹分配给识别的移动组。旨在克服基于视觉轨迹的固有缺点的新的相似度措施。实验结果表明,拟议的分类方法的有效性及其适应不同交通方案的能力,无需任何手动干预。
translated by 谷歌翻译