作为一种有希望的隐私机器学习方法,联合学习(FL)可以使客户跨客户培训,而不会损害其机密的本地数据。但是,现有的FL方法遇到了不均分布数据的推理性能低的问题,因为它们中的大多数依赖于联合平均(FIDAVG)基于联合的聚合。通过以粗略的方式平均模型参数,FedAvg将局部模型的个体特征黯然失色,这极大地限制了FL的推理能力。更糟糕的是,在每一轮FL培训中,FedAvg向客户端向客户派遣了相同的初始本地模型,这很容易导致对最佳全局模型的局限性搜索。为了解决上述问题,本文提出了一种新颖有效的FL范式,名为FEDMR(联合模型重组)。与传统的基于FedAvg的方法不同,FEDMR的云服务器将收集到的本地型号的每一层层混合,并重组它们以实现新的模型,以供客户端培训。由于在每场FL比赛中进行了细粒度的模型重组和本地培训,FEDMR可以迅速为所有客户找出一个全球最佳模型。全面的实验结果表明,与最先进的FL方法相比,FEDMR可以显着提高推理准确性而不会引起额外的通信开销。
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本文提出了一个最佳的运动计划框架,以自动生成多功能的四足动物跳跃运动(例如,翻转,旋转)。通过质心动力学的跳跃运动被配制为受机器人基诺动力约束的12维黑盒优化问题。基于梯度的方法在解决轨迹优化方面取得了巨大成功(TO),但是,需要先验知识(例如,参考运动,联系时间表),并导致次级最佳解决方案。新提出的框架首先采用了基于启发式的优化方法来避免这些问题。此外,针对机器人地面反作用力(GRF)计划中的基于启发式算法的算法创建了优先级的健身函数,增强收敛性和搜索性能。由于基于启发式的算法通常需要大量的时间,因此计划离线运动并作为运动前库存储。选择器旨在自动选择用用户指定或感知信息作为输入的动作。该框架仅通过几项具有挑战性的跳跃动作在开源迷你室中的简单连续跟踪PD控制器进行了成功验证,包括跳过30厘米高度的窗户形状的障碍物,并在矩形障碍物上与左悬挂式障碍物。 27厘米高。
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主观认知下降(SCD)是阿尔茨海默氏病(AD)的临床前阶段,甚至在轻度认知障碍(MCI)之前就发生。渐进式SCD将转换为MCI,并有可能进一步发展为AD。因此,通过神经成像技术(例如,结构MRI)对进行性SCD的早期鉴定对于AD的早期干预具有巨大的临床价值。但是,现有的基于MRI的机器/深度学习方法通​​常会遇到小样本大小的问题,这对相关的神经影像学分析构成了巨大挑战。我们旨在解决本文的主要问题是如何利用相关领域(例如AD/NC)协助SCD的进展预测。同时,我们担心哪些大脑区域与进行性SCD的识别更加紧密相关。为此,我们提出了一个注意引导自动编码器模型,以进行有效的跨域适应,以促进知识转移从AD到SCD。所提出的模型由四个关键组成部分组成:1)用于学习不同域的共享子空间表示的功能编码模块,2)用于自动定义大脑中定义的兴趣障碍区域的注意模块,3)用于重构的解码模块原始输入,4)用于鉴定脑疾病的分类模块。通过对这四个模块的联合培训,可以学习域不变功能。同时,注意机制可以强调与脑部疾病相关的区域。公开可用的ADNI数据集和私人CLAS数据集的广泛实验证明了该方法的有效性。提出的模型直接可以在CPU上仅5-10秒进行训练和测试,并且适用于具有小数据集的医疗任务。
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Few Shot Instance Segmentation (FSIS) requires models to detect and segment novel classes with limited several support examples. In this work, we explore a simple yet unified solution for FSIS as well as its incremental variants, and introduce a new framework named Reference Twice (RefT) to fully explore the relationship between support/query features based on a Transformer-like framework. Our key insights are two folds: Firstly, with the aid of support masks, we can generate dynamic class centers more appropriately to re-weight query features. Secondly, we find that support object queries have already encoded key factors after base training. In this way, the query features can be enhanced twice from two aspects, i.e., feature-level and instance-level. In particular, we firstly design a mask-based dynamic weighting module to enhance support features and then propose to link object queries for better calibration via cross-attention. After the above steps, the novel classes can be improved significantly over our strong baseline. Additionally, our new framework can be easily extended to incremental FSIS with minor modification. When benchmarking results on the COCO dataset for FSIS, gFSIS, and iFSIS settings, our method achieves a competitive performance compared to existing approaches across different shots, e.g., we boost nAP by noticeable +8.2/+9.4 over the current state-of-the-art FSIS method for 10/30-shot. We further demonstrate the superiority of our approach on Few Shot Object Detection. Code and model will be available.
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Benefiting from the intrinsic supervision information exploitation capability, contrastive learning has achieved promising performance in the field of deep graph clustering recently. However, we observe that two drawbacks of the positive and negative sample construction mechanisms limit the performance of existing algorithms from further improvement. 1) The quality of positive samples heavily depends on the carefully designed data augmentations, while inappropriate data augmentations would easily lead to the semantic drift and indiscriminative positive samples. 2) The constructed negative samples are not reliable for ignoring important clustering information. To solve these problems, we propose a Cluster-guided Contrastive deep Graph Clustering network (CCGC) by mining the intrinsic supervision information in the high-confidence clustering results. Specifically, instead of conducting complex node or edge perturbation, we construct two views of the graph by designing special Siamese encoders whose weights are not shared between the sibling sub-networks. Then, guided by the high-confidence clustering information, we carefully select and construct the positive samples from the same high-confidence cluster in two views. Moreover, to construct semantic meaningful negative sample pairs, we regard the centers of different high-confidence clusters as negative samples, thus improving the discriminative capability and reliability of the constructed sample pairs. Lastly, we design an objective function to pull close the samples from the same cluster while pushing away those from other clusters by maximizing and minimizing the cross-view cosine similarity between positive and negative samples. Extensive experimental results on six datasets demonstrate the effectiveness of CCGC compared with the existing state-of-the-art algorithms.
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In robust Markov decision processes (MDPs), the uncertainty in the transition kernel is addressed by finding a policy that optimizes the worst-case performance over an uncertainty set of MDPs. While much of the literature has focused on discounted MDPs, robust average-reward MDPs remain largely unexplored. In this paper, we focus on robust average-reward MDPs, where the goal is to find a policy that optimizes the worst-case average reward over an uncertainty set. We first take an approach that approximates average-reward MDPs using discounted MDPs. We prove that the robust discounted value function converges to the robust average-reward as the discount factor $\gamma$ goes to $1$, and moreover, when $\gamma$ is large, any optimal policy of the robust discounted MDP is also an optimal policy of the robust average-reward. We further design a robust dynamic programming approach, and theoretically characterize its convergence to the optimum. Then, we investigate robust average-reward MDPs directly without using discounted MDPs as an intermediate step. We derive the robust Bellman equation for robust average-reward MDPs, prove that the optimal policy can be derived from its solution, and further design a robust relative value iteration algorithm that provably finds its solution, or equivalently, the optimal robust policy.
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Domain adaptive detection aims to improve the generalization of detectors on target domain. To reduce discrepancy in feature distributions between two domains, recent approaches achieve domain adaption through feature alignment in different granularities via adversarial learning. However, they neglect the relationship between multiple granularities and different features in alignment, degrading detection. Addressing this, we introduce a unified multi-granularity alignment (MGA)-based detection framework for domain-invariant feature learning. The key is to encode the dependencies across different granularities including pixel-, instance-, and category-levels simultaneously to align two domains. Specifically, based on pixel-level features, we first develop an omni-scale gated fusion (OSGF) module to aggregate discriminative representations of instances with scale-aware convolutions, leading to robust multi-scale detection. Besides, we introduce multi-granularity discriminators to identify where, either source or target domains, different granularities of samples come from. Note that, MGA not only leverages instance discriminability in different categories but also exploits category consistency between two domains for detection. Furthermore, we present an adaptive exponential moving average (AEMA) strategy that explores model assessments for model update to improve pseudo labels and alleviate local misalignment problem, boosting detection robustness. Extensive experiments on multiple domain adaption scenarios validate the superiority of MGA over other approaches on FCOS and Faster R-CNN detectors. Code will be released at https://github.com/tiankongzhang/MGA.
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Differentiable Architecture Search (DARTS) has attracted considerable attention as a gradient-based Neural Architecture Search (NAS) method. Since the introduction of DARTS, there has been little work done on adapting the action space based on state-of-art architecture design principles for CNNs. In this work, we aim to address this gap by incrementally augmenting the DARTS search space with micro-design changes inspired by ConvNeXt and studying the trade-off between accuracy, evaluation layer count, and computational cost. To this end, we introduce the Pseudo-Inverted Bottleneck conv block intending to reduce the computational footprint of the inverted bottleneck block proposed in ConvNeXt. Our proposed architecture is much less sensitive to evaluation layer count and outperforms a DARTS network with similar size significantly, at layer counts as small as 2. Furthermore, with less layers, not only does it achieve higher accuracy with lower GMACs and parameter count, GradCAM comparisons show that our network is able to better detect distinctive features of target objects compared to DARTS.
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Automatic font generation without human experts is a practical and significant problem, especially for some languages that consist of a large number of characters. Existing methods for font generation are often in supervised learning. They require a large number of paired data, which are labor-intensive and expensive to collect. In contrast, common unsupervised image-to-image translation methods are not applicable to font generation, as they often define style as the set of textures and colors. In this work, we propose a robust deformable generative network for unsupervised font generation (abbreviated as DGFont++). We introduce a feature deformation skip connection (FDSC) to learn local patterns and geometric transformations between fonts. The FDSC predicts pairs of displacement maps and employs the predicted maps to apply deformable convolution to the low-level content feature maps. The outputs of FDSC are fed into a mixer to generate final results. Moreover, we introduce contrastive self-supervised learning to learn a robust style representation for fonts by understanding the similarity and dissimilarities of fonts. To distinguish different styles, we train our model with a multi-task discriminator, which ensures that each style can be discriminated independently. In addition to adversarial loss, another two reconstruction losses are adopted to constrain the domain-invariant characteristics between generated images and content images. Taking advantage of FDSC and the adopted loss functions, our model is able to maintain spatial information and generates high-quality character images in an unsupervised manner. Experiments demonstrate that our model is able to generate character images of higher quality than state-of-the-art methods.
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Function approximation (FA) has been a critical component in solving large zero-sum games. Yet, little attention has been given towards FA in solving \textit{general-sum} extensive-form games, despite them being widely regarded as being computationally more challenging than their fully competitive or cooperative counterparts. A key challenge is that for many equilibria in general-sum games, no simple analogue to the state value function used in Markov Decision Processes and zero-sum games exists. In this paper, we propose learning the \textit{Enforceable Payoff Frontier} (EPF) -- a generalization of the state value function for general-sum games. We approximate the optimal \textit{Stackelberg extensive-form correlated equilibrium} by representing EPFs with neural networks and training them by using appropriate backup operations and loss functions. This is the first method that applies FA to the Stackelberg setting, allowing us to scale to much larger games while still enjoying performance guarantees based on FA error. Additionally, our proposed method guarantees incentive compatibility and is easy to evaluate without having to depend on self-play or approximate best-response oracles.
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