最近的研究表明,基于神经网络的深度推荐系统容易受到对抗性攻击的影响,攻击者可以将精心制作的虚假用户配置文件(即,伪造用户与之互动的一组项目)注入目标推荐系统,以实现恶意目的,例如促进或降低一组目标项目。由于安全性和隐私问题,在黑框设置下执行对抗性攻击更为实用,在黑框设置下,攻击者无法轻松访问目标系统的体系结构/参数和培训数据。但是,在Black-Box设置下生成高质量的假用户配置文件,对于目标系统的资源有限,这是一项挑战。为了应对这一挑战,在这项工作中,我们通过利用项目的属性信息(即项目知识图)引入了一种新颖的策略,这些信息可以公开访问并提供丰富的辅助知识来增强伪造用户配置文件的产生。更具体地说,我们提出了一项知识增强的黑框攻击框架(KGATTACK),以通过深度强化学习技术有效地学习攻击政策,其中知识图无缝集成到层次结构策略网络中,以生成伪造的用户配置文件,以表演对抗性黑色 - 黑色 - - 黑色 - 黑色 - 盒子攻击。在各种现实世界数据集上进行的全面实验证明了在黑框设置下提出的攻击框架的有效性。
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密集的视频字幕(DVC)的任务旨在为一个视频中的多个事件制作带有时间戳的字幕。语义信息对于DVC的本地化和描述都起着重要作用。我们提出了基于编码编码框架的语义辅助密集的视频字幕模型。在编码阶段,我们设计了一个概念检测器来提取语义信息,然后将其与多模式的视觉特征融合在一起,以充分代表输入视频。在解码阶段,我们设计了一个与本地化和字幕的分类头,以提供语义监督。我们的方法在DVC评估指标下对Youmakeup数据集进行了重大改进,并在PIC 4TH挑战的化妆密集视频字幕(MDVC)任务中实现了高性能。
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视觉接地是定位自然语言表达式指示的目标的任务。现有方法将通用对象检测框架扩展到此问题。它们将视觉接地基于预先生成的提案或锚点的特征,并将这些功能与文本嵌入融合,以找到文本提到的目标。但是,对这些预定义位置的视觉特征进行建模可能无法完全利用文本查询中的视觉上下文和属性信息,从而限制其性能。在本文中,我们提出了一个基于变压器的框架,以通过建立文本条件的判别特征和执行多阶段的跨模式推理来进行准确的视觉接地。具体而言,我们开发了一个视觉语言验证模块,以将视觉特征集中在与文本描述相关的区域上,同时抑制了无关区域。还设计了一种语言指导的特征编码器来汇总目标对象的视觉上下文,以提高对象的独特性。为了从编码的视觉特征中检索目标,我们进一步提出了一个多阶段的跨模式解码器,以迭代地推测图像和文本之间的相关性,以进行准确的目标定位。在五个广泛使用的数据集上进行的广泛实验验证了我们提出的组件的功效,并证明了最先进的性能。我们的代码在https://github.com/yangli18/vltvg上公开。
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视频标题的当前度量主要基于参考和候选字幕之间的文本级别比较。然而,它们具有一些不可能的缺点,例如,它们不能在没有参考的情况下处理视频,并且由于视频到文本的一对多性质和忽视视觉相关性的一对多性质,它们可能导致偏见的评估。从人类评估者的观点来看,高质量的标题应与提供的视频一致,但不一定类似于文字或语义中的参考。灵感来自人类评估,我们提出了Emscore(基于匹配的分数),是视频字幕的一种新颖的无参考度量,其直接测量视频和候选字幕之间的相似性。受益于最近的大规模预训练模型的发展,我们利用了一个良好的预先训练的视觉语言模型来提取用于计算Emscore的视觉和语言嵌入。具体地,Emscore将粗粒(视频和标题)和细粒度(帧和单词)水平的匹配分数组合,这将考虑到视频的整体理解和详细特征。此外,考虑到潜在的信息增益,Emscore可以灵活地扩展到人类标记的参考可用的条件。最后但并非最不重要的是,我们收集Vatex-eval和ActivityNet-Foil数据集以系统地评估现有的度量标准。 Vatex-emp实验表明,Emscore具有更高的人类相关性和较低的参考依赖性。 ActivityNet-Foil实验验证Emscore可以有效地识别“幻觉”标题。将释放数据集以促进视频标题度量的开发。代码可在:https://github.com/shiyaya/emcore。
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Recent one-stage object detectors follow a per-pixel prediction approach that predicts both the object category scores and boundary positions from every single grid location. However, the most suitable positions for inferring different targets, i.e., the object category and boundaries, are generally different. Predicting all these targets from the same grid location thus may lead to sub-optimal results. In this paper, we analyze the suitable inference positions for object category and boundaries, and propose a prediction-target-decoupled detector named PDNet to establish a more flexible detection paradigm. Our PDNet with the prediction decoupling mechanism encodes different targets separately in different locations. A learnable prediction collection module is devised with two sets of dynamic points, i.e., dynamic boundary points and semantic points, to collect and aggregate the predictions from the favorable regions for localization and classification. We adopt a two-step strategy to learn these dynamic point positions, where the prior positions are estimated for different targets first, and the network further predicts residual offsets to the positions with better perceptions of the object properties. Extensive experiments on the MS COCO benchmark demonstrate the effectiveness and efficiency of our method. With a single ResNeXt-64x4d-101-DCN as the backbone, our detector achieves 50.1 AP with single-scale testing, which outperforms the state-of-the-art methods by an appreciable margin under the same experimental settings.Moreover, our detector is highly efficient as a one-stage framework. Our code is public at https://github.com/yangli18/PDNet.
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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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