在本文中,我们从优化的角度研究了对比度学习,旨在分析和解决现有的对比学习方法的基本问题,这些方法依靠大批量大小或大型矢量词典。我们考虑了对比度学习的全球目标,该目标将每个正对与锚点的所有负对对比。从优化的角度来看,我们解释了为什么诸如SIMCLR之类的现有方法需要大批量大小才能获得令人满意的结果。为了消除此类要求,我们提出了一种记忆有效的随机优化算法,用于求解名为SOGCLR的对比度学习的全局目标。我们表明,在足够数量的迭代次数之后,在合理条件下,其优化误差可以忽略不计,或者对于稍有不同的全局对比目标而减少。从经验上讲,我们证明具有小批量大小的SOGCLR(例如256)可以在Imagenet-1k上的自我监督学习任务上获得与具有较大批量大小(例如8192)的SIMCLR相似的性能。我们还试图证明所提出的优化技术是通用的,可以应用于解决其他对比损失,例如双峰对比度学习的双向对比损失。提出的方法是在我们开源的图书馆libauc(www.libauc.org)中实现的。
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最近,模型 - 不可知的元学习(MAML)已经获得了巨大的关注。然而,MAML的随机优化仍然不成熟。 MAML的现有算法利用“剧集”思想,通过对每个迭代的每个采样任务进行采样和一些数据点来更新元模型。但是,它们不一定能够以恒定的小批量大小保证收敛,或者需要在每次迭代时处理大量任务,这对于持续学习或跨设备联合学习不可行,其中仅提供少量任务每次迭代或每轮。本文通过(i)提出了与消失收敛误差的有效的基于内存的随机算法提出了基于存储的基于存储器的随机算法,这只需要采样恒定数量的任务和恒定数量的每次迭代数据样本; (ii)提出基于通信的分布式内存基于存储器的MAML算法,用于跨设备(带客户端采样)和跨筒仓(无客户采样)设置中的个性化联合学习。理论结果显着改善了MAML的优化理论,实证结果也证实了理论。
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本文重点介绍了解决光滑非凸强凹入最小问题的随机方法,这导致了由于其深度学习中的潜在应用而受到越来越长的关注(例如,深度AUC最大化,分布鲁棒优化)。然而,大多数现有算法在实践中都很慢,并且它们的分析围绕到几乎静止点的收敛。我们考虑利用Polyak-\ L Ojasiewicz(PL)条件来设计更快的随机算法,具有更强的收敛保证。尽管已经用于设计许多随机最小化算法的PL条件,但它们对非凸敏最大优化的应用仍然罕见。在本文中,我们提出并分析了基于近端的跨越时代的方法的通用框架,许多众所周知的随机更新嵌入。以{\ BF原始物镜差和二元间隙}的方式建立快速收敛。与现有研究相比,(i)我们的分析基于一个新的Lyapunov函数,包括原始物理差距和正则化功能的二元间隙,(ii)结果更加全面,提高了更好的依赖性的速率不同假设下的条件号。我们还开展深层和非深度学习实验,以验证我们的方法的有效性。
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Graph Neural Networks (GNNs) have shown satisfying performance on various graph learning tasks. To achieve better fitting capability, most GNNs are with a large number of parameters, which makes these GNNs computationally expensive. Therefore, it is difficult to deploy them onto edge devices with scarce computational resources, e.g., mobile phones and wearable smart devices. Knowledge Distillation (KD) is a common solution to compress GNNs, where a light-weighted model (i.e., the student model) is encouraged to mimic the behavior of a computationally expensive GNN (i.e., the teacher GNN model). Nevertheless, most existing GNN-based KD methods lack fairness consideration. As a consequence, the student model usually inherits and even exaggerates the bias from the teacher GNN. To handle such a problem, we take initial steps towards fair knowledge distillation for GNNs. Specifically, we first formulate a novel problem of fair knowledge distillation for GNN-based teacher-student frameworks. Then we propose a principled framework named RELIANT to mitigate the bias exhibited by the student model. Notably, the design of RELIANT is decoupled from any specific teacher and student model structures, and thus can be easily adapted to various GNN-based KD frameworks. We perform extensive experiments on multiple real-world datasets, which corroborates that RELIANT achieves less biased GNN knowledge distillation while maintaining high prediction utility.
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To generate high quality rendering images for real time applications, it is often to trace only a few samples-per-pixel (spp) at a lower resolution and then supersample to the high resolution. Based on the observation that the rendered pixels at a low resolution are typically highly aliased, we present a novel method for neural supersampling based on ray tracing 1/4-spp samples at the high resolution. Our key insight is that the ray-traced samples at the target resolution are accurate and reliable, which makes the supersampling an interpolation problem. We present a mask-reinforced neural network to reconstruct and interpolate high-quality image sequences. First, a novel temporal accumulation network is introduced to compute the correlation between current and previous features to significantly improve their temporal stability. Then a reconstruct network based on a multi-scale U-Net with skip connections is adopted for reconstruction and generation of the desired high-resolution image. Experimental results and comparisons have shown that our proposed method can generate higher quality results of supersampling, without increasing the total number of ray-tracing samples, over current state-of-the-art methods.
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Panoptic Part Segmentation (PPS) unifies panoptic segmentation and part segmentation into one task. Previous works utilize separated approaches to handle thing, stuff, and part predictions without shared computation and task association. We aim to unify these tasks at the architectural level, designing the first end-to-end unified framework named Panoptic-PartFormer. Moreover, we find the previous metric PartPQ biases to PQ. To handle both issues, we make the following contributions: Firstly, we design a meta-architecture that decouples part feature and things/stuff feature, respectively. We model things, stuff, and parts as object queries and directly learn to optimize all three forms of prediction as a unified mask prediction and classification problem. We term our model as Panoptic-PartFormer. Secondly, we propose a new metric Part-Whole Quality (PWQ) to better measure such task from both pixel-region and part-whole perspectives. It can also decouple the error for part segmentation and panoptic segmentation. Thirdly, inspired by Mask2Former, based on our meta-architecture, we propose Panoptic-PartFormer++ and design a new part-whole cross attention scheme to further boost part segmentation qualities. We design a new part-whole interaction method using masked cross attention. Finally, the extensive ablation studies and analysis demonstrate the effectiveness of both Panoptic-PartFormer and Panoptic-PartFormer++. Compared with previous Panoptic-PartFormer, our Panoptic-PartFormer++ achieves 2% PartPQ and 3% PWQ improvements on the Cityscapes PPS dataset and 5% PartPQ on the Pascal Context PPS dataset. On both datasets, Panoptic-PartFormer++ achieves new state-of-the-art results with a significant cost drop of 70% on GFlops and 50% on parameters. Our models can serve as a strong baseline and aid future research in PPS. Code will be available.
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An increasing number of public datasets have shown a marked clinical impact on assessing anatomical structures. However, each of the datasets is small, partially labeled, and rarely investigates severe tumor subjects. Moreover, current models are limited to segmenting specific organs/tumors, which can not be extended to novel domains and classes. To tackle these limitations, we introduce embedding learned from Contrastive Language-Image Pre-training (CLIP) to segmentation models, dubbed the CLIP-Driven Universal Model. The Universal Model can better segment 25 organs and 6 types of tumors by exploiting the semantic relationship between abdominal structures. The model is developed from an assembly of 14 datasets with 3,410 CT scans and evaluated on 6,162 external CT scans from 3 datasets. We rank first on the public leaderboard of the Medical Segmentation Decathlon (MSD) and achieve the state-of-the-art results on Beyond The Cranial Vault (BTCV). Compared with dataset-specific models, the Universal Model is computationally more efficient (6x faster), generalizes better to CT scans from varying sites, and shows stronger transfer learning performance on novel tasks. The design of CLIP embedding enables the Universal Model to be easily extended to new classes without catastrophically forgetting the previously learned classes.
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This paper illustrates the technologies of user next intent prediction with a concept knowledge graph. The system has been deployed on the Web at Alipay, serving more than 100 million daily active users. Specifically, we propose AlipayKG to explicitly characterize user intent, which is an offline concept knowledge graph in the Life-Service domain modeling the historical behaviors of users, the rich content interacted by users and the relations between them. We further introduce a Transformer-based model which integrates expert rules from the knowledge graph to infer the online user's next intent. Experimental results demonstrate that the proposed system can effectively enhance the performance of the downstream tasks while retaining explainability.
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Medical image segmentation (MIS) is essential for supporting disease diagnosis and treatment effect assessment. Despite considerable advances in artificial intelligence (AI) for MIS, clinicians remain skeptical of its utility, maintaining low confidence in such black box systems, with this problem being exacerbated by low generalization for out-of-distribution (OOD) data. To move towards effective clinical utilization, we propose a foundation model named EvidenceCap, which makes the box transparent in a quantifiable way by uncertainty estimation. EvidenceCap not only makes AI visible in regions of uncertainty and OOD data, but also enhances the reliability, robustness, and computational efficiency of MIS. Uncertainty is modeled explicitly through subjective logic theory to gather strong evidence from features. We show the effectiveness of EvidenceCap in three segmentation datasets and apply it to the clinic. Our work sheds light on clinical safe applications and explainable AI, and can contribute towards trustworthiness in the medical domain.
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Depression is a leading cause of death worldwide, and the diagnosis of depression is nontrivial. Multimodal learning is a popular solution for automatic diagnosis of depression, and the existing works suffer two main drawbacks: 1) the high-order interactions between different modalities can not be well exploited; and 2) interpretability of the models are weak. To remedy these drawbacks, we propose a multimodal multi-order factor fusion (MMFF) method. Our method can well exploit the high-order interactions between different modalities by extracting and assembling modality factors under the guide of a shared latent proxy. We conduct extensive experiments on two recent and popular datasets, E-DAIC-WOZ and CMDC, and the results show that our method achieve significantly better performance compared with other existing approaches. Besides, by analyzing the process of factor assembly, our model can intuitively show the contribution of each factor. This helps us understand the fusion mechanism.
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