图形预训练策略一直在图形挖掘社区吸引人们的注意力，因为它们在没有任何标签信息的情况下在参数化图形神经网络（GNN）方面的灵活性。关键思想在于通过预测从输入图中提取的掩蔽图信号来编码有价值的信息。为了平衡各种图形信号的重要性（例如节点，边缘，子图），现有方法主要是通过引入超参数来重新进行图形信号的重要性来进行手工设计的。然而，人类对亚最佳高参数的干预通常会注入额外的偏见，并在下游应用中降低了概括性能。本文从新的角度解决了这些局限性，即为预培训GNN提供课程。我们提出了一个名为Mentorgnn的端到端模型，该模型旨在监督具有不同结构和不同特征空间的图表的GNN的预训练过程。为了理解不同粒度的异质图信号，我们提出了一种课程学习范式，该课程自动重新贴出图形信号，以确保对目标域进行良好的概括。此外，我们通过在预先训练的GNN的概括误差上得出自然且可解释的上限，从而对关系数据（即图形）的域自适应问题（即图形）发出了新的启示。有关大量真实图的广泛实验验证并验证了Mentorgnn的性能。

浅GNN倾向于与具有缺失功能的大型图形或图形相关性能。因此，有必要增加GNN的深度（即，层数），以捕获对输入数据的更多潜在知识。另一方面，包括GNN中的更多层通常会降低其性能，例如消失的梯度和过度平滑。现有的方法（例如，配对和DropEdge）主要集中于解决过度厚度，但它们遭受了一些缺点，例如需要难以提高知识或进行大型培训随机性。此外，这些方法只是将重新连接到解决消失的梯度。他们忽略了一个重要的事实：与从遥远的邻居中收集的信息相比，与从1跳和2跳的邻居收集的信息相比，从遥远的邻居收集的信息变得占主导地位，从而导致严重的性能退化，从而使其占主导地位。在本文中，我们首先深入研究了Resnet的架构，并分析了为什么Resnet最不适合更深的GNN。然后，我们提出了一种新的残留体系结构，以减轻重新系统造成的负面影响。为了解决这些现有方法的缺点，我们介绍了名为TGCL的拓扑引导的图形对比损失。它利用节点拓扑信息，并通过对比度学习正则化将连接的节点对靠近，以获得歧视性节点表示。将新的残留体系结构与TGCL相结合，提出了一个名为更深的GNNS的端到端框架。对现实世界数据集的广泛实验证明了与最先进的基线相比，更深型GXX的有效性和效率。

随着大数据在多个高影响应用程序中的出现，我们经常面临复杂异质性的挑战。新收集的数据通常由多种模态组成，并具有多个标签，因此表现出多种类型的异质性的共存。尽管最先进的技术擅长使用足够的标签信息对复杂的异质性进行建模，但是在实际应用中获得的标签信息可能非常昂贵。最近，研究人员通过利用丰富的未标记数据，非常关注对比度学习的出色表现。但是，对比度学习上的现有工作无法解决虚假负面对的问题，即，如果某些“负”对具有相同的标签，则可能具有相似的表示。为了克服这些问题，在本文中，我们提出了一个统一的异质学习框架，该框架结合了加权的无监督对比损失和加权监督的对比损失，以模拟多种类型的异质性。我们首先提供了理论分析，表明在存在假负对的情况下，香草对比度学习损失很容易导致次优的解决方案，而拟议的加权损失可以自动根据学习表示的相似性自动调整重量，从而减轻这种情况以减轻这种情况问题。现实世界数据集的实验结果证明了对多种类型的异质性建模所提出的框架的有效性和效率。

Masked image modeling (MIM) performs strongly in pre-training large vision Transformers (ViTs). However, small models that are critical for real-world applications cannot or only marginally benefit from this pre-training approach. In this paper, we explore distillation techniques to transfer the success of large MIM-based pre-trained models to smaller ones. We systematically study different options in the distillation framework, including distilling targets, losses, input, network regularization, sequential distillation, etc, revealing that: 1) Distilling token relations is more effective than CLS token- and feature-based distillation; 2) An intermediate layer of the teacher network as target perform better than that using the last layer when the depth of the student mismatches that of the teacher; 3) Weak regularization is preferred; etc. With these findings, we achieve significant fine-tuning accuracy improvements over the scratch MIM pre-training on ImageNet-1K classification, using all the ViT-Tiny, ViT-Small, and ViT-base models, with +4.2%/+2.4%/+1.4% gains, respectively. Our TinyMIM model of base size achieves 52.2 mIoU in AE20K semantic segmentation, which is +4.1 higher than the MAE baseline. Our TinyMIM model of tiny size achieves 79.6% top-1 accuracy on ImageNet-1K image classification, which sets a new record for small vision models of the same size and computation budget. This strong performance suggests an alternative way for developing small vision Transformer models, that is, by exploring better training methods rather than introducing inductive biases into architectures as in most previous works. Code is available at https://github.com/OliverRensu/TinyMIM.

Dataset distillation has emerged as a prominent technique to improve data efficiency when training machine learning models. It encapsulates the knowledge from a large dataset into a smaller synthetic dataset. A model trained on this smaller distilled dataset can attain comparable performance to a model trained on the original training dataset. However, the existing dataset distillation techniques mainly aim at achieving the best trade-off between resource usage efficiency and model utility. The security risks stemming from them have not been explored. This study performs the first backdoor attack against the models trained on the data distilled by dataset distillation models in the image domain. Concretely, we inject triggers into the synthetic data during the distillation procedure rather than during the model training stage, where all previous attacks are performed. We propose two types of backdoor attacks, namely NAIVEATTACK and DOORPING. NAIVEATTACK simply adds triggers to the raw data at the initial distillation phase, while DOORPING iteratively updates the triggers during the entire distillation procedure. We conduct extensive evaluations on multiple datasets, architectures, and dataset distillation techniques. Empirical evaluation shows that NAIVEATTACK achieves decent attack success rate (ASR) scores in some cases, while DOORPING reaches higher ASR scores (close to 1.0) in all cases. Furthermore, we conduct a comprehensive ablation study to analyze the factors that may affect the attack performance. Finally, we evaluate multiple defense mechanisms against our backdoor attacks and show that our attacks can practically circumvent these defense mechanisms.

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.

As one of the prevalent methods to achieve automation systems, Imitation Learning (IL) presents a promising performance in a wide range of domains. However, despite the considerable improvement in policy performance, the corresponding research on the explainability of IL models is still limited. Inspired by the recent approaches in explainable artificial intelligence methods, we proposed a model-agnostic explaining framework for IL models called R2RISE. R2RISE aims to explain the overall policy performance with respect to the frames in demonstrations. It iteratively retrains the black-box IL model from the randomized masked demonstrations and uses the conventional evaluation outcome environment returns as the coefficient to build an importance map. We also conducted experiments to investigate three major questions concerning frames' importance equality, the effectiveness of the importance map, and connections between importance maps from different IL models. The result shows that R2RISE successfully distinguishes important frames from the demonstrations.

Compressed videos often exhibit visually annoying artifacts, known as Perceivable Encoding Artifacts (PEAs), which dramatically degrade video visual quality. Subjective and objective measures capable of identifying and quantifying various types of PEAs are critical in improving visual quality. In this paper, we investigate the influence of four spatial PEAs (i.e. blurring, blocking, bleeding, and ringing) and two temporal PEAs (i.e. flickering and floating) on video quality. For spatial artifacts, we propose a visual saliency model with a low computational cost and higher consistency with human visual perception. In terms of temporal artifacts, self-attention based TimeSFormer is improved to detect temporal artifacts. Based on the six types of PEAs, a quality metric called Saliency-Aware Spatio-Temporal Artifacts Measurement (SSTAM) is proposed. Experimental results demonstrate that the proposed method outperforms state-of-the-art metrics. We believe that SSTAM will be beneficial for optimizing video coding techniques.

Transformer has achieved impressive successes for various computer vision tasks. However, most of existing studies require to pretrain the Transformer backbone on a large-scale labeled dataset (e.g., ImageNet) for achieving satisfactory performance, which is usually unavailable for medical images. Additionally, due to the gap between medical and natural images, the improvement generated by the ImageNet pretrained weights significantly degrades while transferring the weights to medical image processing tasks. In this paper, we propose Bootstrap Own Latent of Transformer (BOLT), a self-supervised learning approach specifically for medical image classification with the Transformer backbone. Our BOLT consists of two networks, namely online and target branches, for self-supervised representation learning. Concretely, the online network is trained to predict the target network representation of the same patch embedding tokens with a different perturbation. To maximally excavate the impact of Transformer from limited medical data, we propose an auxiliary difficulty ranking task. The Transformer is enforced to identify which branch (i.e., online/target) is processing the more difficult perturbed tokens. Overall, the Transformer endeavours itself to distill the transformation-invariant features from the perturbed tokens to simultaneously achieve difficulty measurement and maintain the consistency of self-supervised representations. The proposed BOLT is evaluated on three medical image processing tasks, i.e., skin lesion classification, knee fatigue fracture grading and diabetic retinopathy grading. The experimental results validate the superiority of our BOLT for medical image classification, compared to ImageNet pretrained weights and state-of-the-art self-supervised learning approaches.

When using LiDAR semantic segmentation models for safety-critical applications such as autonomous driving, it is essential to understand and improve their robustness with respect to a large range of LiDAR corruptions. In this paper, we aim to comprehensively analyze the robustness of LiDAR semantic segmentation models under various corruptions. To rigorously evaluate the robustness and generalizability of current approaches, we propose a new benchmark called SemanticKITTI-C, which features 16 out-of-domain LiDAR corruptions in three groups, namely adverse weather, measurement noise and cross-device discrepancy. Then, we systematically investigate 11 LiDAR semantic segmentation models, especially spanning different input representations (e.g., point clouds, voxels, projected images, and etc.), network architectures and training schemes. Through this study, we obtain two insights: 1) We find out that the input representation plays a crucial role in robustness. Specifically, under specific corruptions, different representations perform variously. 2) Although state-of-the-art methods on LiDAR semantic segmentation achieve promising results on clean data, they are less robust when dealing with noisy data. Finally, based on the above observations, we design a robust LiDAR segmentation model (RLSeg) which greatly boosts the robustness with simple but effective modifications. It is promising that our benchmark, comprehensive analysis, and observations can boost future research in robust LiDAR semantic segmentation for safety-critical applications.