Bilevel programming has recently received attention in the literature, due to a wide range of applications, including reinforcement learning and hyper-parameter optimization. However, it is widely assumed that the underlying bilevel optimization problem is solved either by a single machine or in the case of multiple machines connected in a star-shaped network, i.e., federated learning setting. The latter approach suffers from a high communication cost on the central node (e.g., parameter server) and exhibits privacy vulnerabilities. Hence, it is of interest to develop methods that solve bilevel optimization problems in a communication-efficient decentralized manner. To that end, this paper introduces a penalty function based decentralized algorithm with theoretical guarantees for this class of optimization problems. Specifically, a distributed alternating gradient-type algorithm for solving consensus bilevel programming over a decentralized network is developed. A key feature of the proposed algorithm is to estimate the hyper-gradient of the penalty function via decentralized computation of matrix-vector products and few vector communications, which is then integrated within our alternating algorithm to give the finite-time convergence analysis under different convexity assumptions. Owing to the generality of this complexity analysis, our result yields convergence rates for a wide variety of consensus problems including minimax and compositional optimization. Empirical results on both synthetic and real datasets demonstrate that the proposed method works well in practice.
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动机:在超声引导活检过程中检测前列腺癌是具有挑战性的。癌症的高度异质外观,超声伪像的存在和噪声都导致了这些困难。高频超声成像的最新进展 - 微拆卸 - 在高分辨率下大大提高了组织成像的能力。我们的目的是研究专门针对微型启动引导的前列腺癌活检的强大深度学习模型的发展。对于临床采用的模型,一个关键的挑战是设计一种可以确定癌症的解决方案,同时从粗略的组织病理学测量中学习引入弱标签的活检样品。方法:我们使用了从194例接受了前列腺活检的患者中获得的微型图像的数据集。我们使用共同教学范式来训练一个深层模型,以处理标签中的噪声,以及一种证据深度学习方法进行不确定性估计。我们使用准确性与信心的临床相关指标评估了模型的性能。结果:我们的模型实现了对预测不确定性的良好估计,而面积为88 $ \%$。联合结合中的共同教学和证据深度学习的使用比单独单独的不确定性估计明显更好。在不确定性估计中,我们还提供了与最先进的比较。
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Reinforcement learning (RL) gained considerable attention by creating decision-making agents that maximize rewards received from fully observable environments. However, many real-world problems are partially or noisily observable by nature, where agents do not receive the true and complete state of the environment. Such problems are formulated as partially observable Markov decision processes (POMDPs). Some studies applied RL to POMDPs by recalling previous decisions and observations or inferring the true state of the environment from received observations. Nevertheless, aggregating observations and decisions over time is impractical for environments with high-dimensional continuous state and action spaces. Moreover, so-called inference-based RL approaches require large number of samples to perform well since agents eschew uncertainty in the inferred state for the decision-making. Active inference is a framework that is naturally formulated in POMDPs and directs agents to select decisions by minimising expected free energy (EFE). This supplies reward-maximising (exploitative) behaviour in RL, with an information-seeking (exploratory) behaviour. Despite this exploratory behaviour of active inference, its usage is limited to discrete state and action spaces due to the computational difficulty of the EFE. We propose a unified principle for joint information-seeking and reward maximization that clarifies a theoretical connection between active inference and RL, unifies active inference and RL, and overcomes their aforementioned limitations. Our findings are supported by strong theoretical analysis. The proposed framework's superior exploration property is also validated by experimental results on partial observable tasks with high-dimensional continuous state and action spaces. Moreover, the results show that our model solves reward-free problems, making task reward design optional.
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GTFLAT, as a game theory-based add-on, addresses an important research question: How can a federated learning algorithm achieve better performance and training efficiency by setting more effective adaptive weights for averaging in the model aggregation phase? The main objectives for the ideal method of answering the question are: (1) empowering federated learning algorithms to reach better performance in fewer communication rounds, notably in the face of heterogeneous scenarios, and last but not least, (2) being easy to use alongside the state-of-the-art federated learning algorithms as a new module. To this end, GTFLAT models the averaging task as a strategic game among active users. Then it proposes a systematic solution based on the population game and evolutionary dynamics to find the equilibrium. In contrast with existing approaches that impose the weights on the participants, GTFLAT concludes a self-enforcement agreement among clients in a way that none of them is motivated to deviate from it individually. The results reveal that, on average, using GTFLAT increases the top-1 test accuracy by 1.38%, while it needs 21.06% fewer communication rounds to reach the accuracy.
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重要性采样(IS)是一种强大的蒙特卡洛(MC)方法,用于近似积分,例如在贝叶斯推论的背景下。在IS中,从所谓的提案分布中模拟样品,并且该提案的选择是实现高性能的关键。在自适应IS(AIS)方法中,一组建议是迭代改进的。 AIS是一种相关和及时的方法论,尽管仍有许多局限性尚待克服,例如,高维和多模式问题的维度诅咒。此外,汉密尔顿蒙特卡洛(HMC)算法在机器学习和统计数据中变得越来越流行。 HMC具有几个吸引人的特征,例如其探索性行为,尤其是在其他方法遭受的情况下,尤其是在高维目标中。在本文中,我们介绍了新型的汉密尔顿自适应重要性采样(HAIS)方法。 Hais使用平行的HMC链实现了两步自适应过程,每次迭代都合作。拟议的HAI有效地适应了一系列建议,从而提取了HMC的优势。 HAI可以理解为具有额外重采样步骤的通用分层AIS家族的特定实例。 HAIS在高维问题W.R.T.方面取得了重大的绩效提高。最先进的算法。我们讨论了HAI的统计特性,并在两个具有挑战性的例子中显示了其高性能。
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由于临床实践所需的放射学报告和研究是在自由文本叙述中编写和存储的,因此很难提取相对信息进行进一步分析。在这种情况下,自然语言处理(NLP)技术可以促进自动信息提取和自由文本格式转换为结构化数据。近年来,基于深度学习(DL)的模型已适用于NLP实验,并具有令人鼓舞的结果。尽管基于人工神经网络(ANN)和卷积神经网络(CNN)的DL模型具有显着潜力,但这些模型仍面临临床实践中实施的一些局限性。变形金刚是另一种新的DL体系结构,已越来越多地用于改善流程。因此,在这项研究中,我们提出了一种基于变压器的细粒命名实体识别(NER)架构,以进行临床信息提取。我们以自由文本格式收集了88次腹部超声检查报告,并根据我们开发的信息架构进行了注释。文本到文本传输变压器模型(T5)和covive是T5模型的预训练域特异性适应性,用于微调来提取实体和关系,并将输入转换为结构化的格式。我们在这项研究中基于变压器的模型优于先前应用的方法,例如基于Rouge-1,Rouge-2,Rouge-L和BLEU分别为0.816、0.668、0.528和0.743的ANN和CNN模型,同时提供了一个分数可解释的结构化报告。
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自适应梯度算法(例如Adagrad及其变体)在培训深神经网络方面已广受欢迎。尽管许多适合自适应方法的工作都集中在静态的遗憾上,作为实现良好遗憾保证的性能指标,但对这些方法的动态遗憾分析尚不清楚。与静态的遗憾相反,动态遗憾被认为是绩效测量的更强大的概念,因为它明确阐明了环境的非平稳性。在本文中,我们通过动态遗憾的概念在一个强大的凸面设置中浏览了Adagrad(称为M-Adagrad)的一种变体,该遗憾衡量了在线学习者的性能,而不是参考(最佳)解决方案,这可能会改变时间。我们证明了根据最小化序列的路径长度的束缚,该序列基本上反映了环境的非平稳性。此外,我们通过利用每个回合中学习者的多个访问权限来增强动态遗憾。经验结果表明,M-Adagrad在实践中也很好。
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边缘设备上卷积神经网络(CNN)的部署受到性能要求和可用处理能力之间的巨大差距的阻碍。尽管最近的研究在开发网络修剪方法以减少CNN的计算开销方面取得了长足的进步,但仍然存在相当大的准确性损失,尤其是在高修剪比率下。质疑为非封闭网络设计的架构可能对修剪网络没有效,我们建议通过定义新的搜索空间和新颖的搜索目标来搜索架构修剪方法。为了改善修剪网络的概括,我们提出了两个新型的原始孔和prunedlinearaare操作。具体而言,这些操作通过正规化修剪网络的目标函数来缓解不稳定梯度的问题。提出的搜索目标使我们能够培训有关修剪权重元素的体系结构参数。定量分析表明,我们的搜索架构优于在CIFAR-10和Imagenet上最先进的修剪网络中使用的体系结构。就硬件效率而言,PR-DARTS将Mobilenet-V2的准确性从73.44%提高到81.35%(+7.91%提高),并且运行3.87 $ \ times $的速度更快。
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梯度下降优化和反向传播是训练神经网络的最常见方法,但是对于实时应用程序而言,它们在计算上很昂贵,需要高内存资源,并且对于许多网络和大型数据集来说很难收敛。 [伪]培训神经网络的逆模型已成为克服这些问题的强大工具。为了有效地实施这些方法,可以应用结构化修剪来产生稀疏的神经网络。尽管稀疏的神经网络在记忆使用方面有效,但他们的大多数算法都使用相同的满载矩阵计算方法,这些方法对于稀疏矩阵不有效。 Tridiagonal矩阵是用于构建神经网络的常用候选者之一,但它们的灵活性不足以处理不足和过度拟合问题以及概括性能。在本文中,我们引入了一种非对称的三角形矩阵,带有稀疏条目,偏移子和超级对角线以及其[伪]逆计算和决定性计算的算法。这些形式的传统矩阵计算,特别是反转和决定因素的传统算法并非特别对于大型矩阵,例如较大的数据集或更深的网络。开发了下三角矩阵的分解,并将原始矩阵分解为一组矩阵,其中计算其反向矩阵。对于不存在矩阵逆的情况,提供了至少平方型伪为。本方法是直接例程,即在可预测数量的操作中执行,该操作已针对大小变化的随机生成的矩阵进行了测试。当矩阵的大小增加时,该结果表明计算成本的显着改善。
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随着自主系统成为我们日常生活的一部分,确保其信任度至关重要。有许多用于证明可信赖性的技术。所有这些技术的共同点是需要阐明规格。在本文中,我们对规格进行了广泛的看法,专注于顶级要求,包括但不限于功能,安全性,安全性和其他非功能性属性。本文的主要贡献是对于与指定可信度相关的自主系统社区的一系列高级智力挑战。我们还描述了有关自主系统的许多应用程序域的独特规范挑战。
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