由于其在许多有影响力的领域中的广泛应用，归因网络上的图形异常检测已成为普遍的研究主题。在现实情况下，属性网络中的节点和边缘通常显示出不同的异质性，即不同类型的节点的属性显示出大量的多样性，不同类型的关系表示多种含义。在这些网络中，异常在异质性的各个角度上的表现通常与大多数不同。但是，现有的图异常检测方法不能利用归因网络中的异质性，这与异常检测高度相关。鉴于这个问题，我们提出了前方的提议：基于编码器解码器框架的异质性无监督图异常检测方法。具体而言，对于编码器，我们设计了三个关注级别，即属性级别，节点类型级别和边缘级别的关注，以捕获网络结构的异质性，节点属性和单个节点的信息。在解码器中，我们利用结构，属性和节点类型重建项来获得每个节点的异常得分。广泛的实验表明，与无监督环境中的艺术品相比，在几个现实世界中的异质信息网络上，前方的优势。进一步的实验验证了我们三重注意力，模型骨干和解码器的有效性和鲁棒性。

知识图嵌入（KGE）旨在将实体和关系映射到低维空间，并成为知识图完成的\ textit {de-facto}标准。大多数现有的KGE方法都受到稀疏挑战的困扰，在这种挑战中，很难预测在知识图中频繁的实体。在这项工作中，我们提出了一个新颖的框架KRACL，以减轻具有图表和对比度学习的KG中广泛的稀疏性。首先，我们建议知识关系网络（KRAT）通过同时将相邻的三元组投射到不同的潜在空间，并通过注意机制共同汇总信息来利用图形上下文。 KRAT能够捕获不同上下文三联的微妙的语义信息和重要性，并利用知识图中的多跳信息。其次，我们通过将对比度损失与跨熵损失相结合，提出知识对比损失，这引入了更多的负样本，从而丰富了对稀疏实体的反馈。我们的实验表明，KRACL在各种标准知识基准中取得了卓越的结果，尤其是在WN18RR和NELL-995上，具有大量低级内实体。广泛的实验还具有KRACL在处理稀疏知识图和鲁棒性三元组的鲁棒性方面的有效性。

Twitter机器人检测已成为打击错误信息，促进社交媒体节制并保持在线话语的完整性的越来越重要的任务。最先进的机器人检测方法通常利用Twitter网络的图形结构，在面对传统方法无法检测到的新型Twitter机器人时，它们表现出令人鼓舞的性能。但是，现有的Twitter机器人检测数据集很少是基于图形的，即使这些基于图形的数据集也遭受有限的数据集量表，不完整的图形结构以及低注释质量。实际上，缺乏解决这些问题的大规模基于图的Twitter机器人检测基准，严重阻碍了基于图形的机器人检测方法的开发和评估。在本文中，我们提出了Twibot-22，这是一个综合基于图的Twitter机器人检测基准，它显示了迄今为止最大的数据集，在Twitter网络上提供了多元化的实体和关系，并且与现有数据集相比具有更好的注释质量。此外，我们重新实施35代表性的Twitter机器人检测基线，并在包括Twibot-22在内的9个数据集上进行评估，以促进对模型性能和对研究进度的整体了解的公平比较。为了促进进一步的研究，我们将所有实施的代码和数据集巩固到Twibot-22评估框架中，研究人员可以在其中始终如一地评估新的模型和数据集。 Twibot-22 Twitter机器人检测基准和评估框架可在https://twibot22.github.io/上公开获得。

建模政治参与者的思想视角是许多下游任务中的应用中的计算政治科学的重要任务。现有方法通常限于文本数据和投票记录，而他们忽视了丰富的社会背景和对整体评价的宝贵专家知识。在本文中，我们提出了一个代表性学习框架，政治行为者共同利用了社会背景和专家知识。具体而言，我们检索和提取关于立法者的事实陈述，以利用社会背景信息。然后，我们构建异构信息网络以合并社会背景并使用关系图形神经网络来学习立法器表示。最后，我们用三个目标训练我们的模型，以与专家知识，模型意识形态阶段一致性，模拟回声室现象的表现学习。广泛的实验表明，我们的学到的陈述在三个下游任务中成功地推动了最先进的。进一步分析证明了学到的立法者代表与各种社会政治因素之间的相关性，以及建立了建模政治行动者的社会背景和专业知识的必要性。

Although many studies have successfully applied transfer learning to medical image segmentation, very few of them have investigated the selection strategy when multiple source tasks are available for transfer. In this paper, we propose a prior knowledge guided and transferability based framework to select the best source tasks among a collection of brain image segmentation tasks, to improve the transfer learning performance on the given target task. The framework consists of modality analysis, RoI (region of interest) analysis, and transferability estimation, such that the source task selection can be refined step by step. Specifically, we adapt the state-of-the-art analytical transferability estimation metrics to medical image segmentation tasks and further show that their performance can be significantly boosted by filtering candidate source tasks based on modality and RoI characteristics. Our experiments on brain matter, brain tumor, and white matter hyperintensities segmentation datasets reveal that transferring from different tasks under the same modality is often more successful than transferring from the same task under different modalities. Furthermore, within the same modality, transferring from the source task that has stronger RoI shape similarity with the target task can significantly improve the final transfer performance. And such similarity can be captured using the Structural Similarity index in the label space.

Modern deep neural networks have achieved superhuman performance in tasks from image classification to game play. Surprisingly, these various complex systems with massive amounts of parameters exhibit the same remarkable structural properties in their last-layer features and classifiers across canonical datasets. This phenomenon is known as "Neural Collapse," and it was discovered empirically by Papyan et al. \cite{Papyan20}. Recent papers have theoretically shown the global solutions to the training network problem under a simplified "unconstrained feature model" exhibiting this phenomenon. We take a step further and prove the Neural Collapse occurrence for deep linear network for the popular mean squared error (MSE) and cross entropy (CE) loss. Furthermore, we extend our research to imbalanced data for MSE loss and present the first geometric analysis for Neural Collapse under this setting.

In this paper we derive a PAC-Bayesian-Like error bound for a class of stochastic dynamical systems with inputs, namely, for linear time-invariant stochastic state-space models (stochastic LTI systems for short). This class of systems is widely used in control engineering and econometrics, in particular, they represent a special case of recurrent neural networks. In this paper we 1) formalize the learning problem for stochastic LTI systems with inputs, 2) derive a PAC-Bayesian-Like error bound for such systems, 3) discuss various consequences of this error bound.

Denoising Diffusion Probabilistic Models (DDPMs) are emerging in text-to-speech (TTS) synthesis because of their strong capability of generating high-fidelity samples. However, their iterative refinement process in high-dimensional data space results in slow inference speed, which restricts their application in real-time systems. Previous works have explored speeding up by minimizing the number of inference steps but at the cost of sample quality. In this work, to improve the inference speed for DDPM-based TTS model while achieving high sample quality, we propose ResGrad, a lightweight diffusion model which learns to refine the output spectrogram of an existing TTS model (e.g., FastSpeech 2) by predicting the residual between the model output and the corresponding ground-truth speech. ResGrad has several advantages: 1) Compare with other acceleration methods for DDPM which need to synthesize speech from scratch, ResGrad reduces the complexity of task by changing the generation target from ground-truth mel-spectrogram to the residual, resulting into a more lightweight model and thus a smaller real-time factor. 2) ResGrad is employed in the inference process of the existing TTS model in a plug-and-play way, without re-training this model. We verify ResGrad on the single-speaker dataset LJSpeech and two more challenging datasets with multiple speakers (LibriTTS) and high sampling rate (VCTK). Experimental results show that in comparison with other speed-up methods of DDPMs: 1) ResGrad achieves better sample quality with the same inference speed measured by real-time factor; 2) with similar speech quality, ResGrad synthesizes speech faster than baseline methods by more than 10 times. Audio samples are available at https://resgrad1.github.io/.

Deep learning has been widely used for protein engineering. However, it is limited by the lack of sufficient experimental data to train an accurate model for predicting the functional fitness of high-order mutants. Here, we develop SESNet, a supervised deep-learning model to predict the fitness for protein mutants by leveraging both sequence and structure information, and exploiting attention mechanism. Our model integrates local evolutionary context from homologous sequences, the global evolutionary context encoding rich semantic from the universal protein sequence space and the structure information accounting for the microenvironment around each residue in a protein. We show that SESNet outperforms state-of-the-art models for predicting the sequence-function relationship on 26 deep mutational scanning datasets. More importantly, we propose a data augmentation strategy by leveraging the data from unsupervised models to pre-train our model. After that, our model can achieve strikingly high accuracy in prediction of the fitness of protein mutants, especially for the higher order variants (> 4 mutation sites), when finetuned by using only a small number of experimental mutation data (<50). The strategy proposed is of great practical value as the required experimental effort, i.e., producing a few tens of experimental mutation data on a given protein, is generally affordable by an ordinary biochemical group and can be applied on almost any protein.

Deep neural networks (DNNs) are found to be vulnerable to adversarial attacks, and various methods have been proposed for the defense. Among these methods, adversarial training has been drawing increasing attention because of its simplicity and effectiveness. However, the performance of the adversarial training is greatly limited by the architectures of target DNNs, which often makes the resulting DNNs with poor accuracy and unsatisfactory robustness. To address this problem, we propose DSARA to automatically search for the neural architectures that are accurate and robust after adversarial training. In particular, we design a novel cell-based search space specially for adversarial training, which improves the accuracy and the robustness upper bound of the searched architectures by carefully designing the placement of the cells and the proportional relationship of the filter numbers. Then we propose a two-stage search strategy to search for both accurate and robust neural architectures. At the first stage, the architecture parameters are optimized to minimize the adversarial loss, which makes full use of the effectiveness of the adversarial training in enhancing the robustness. At the second stage, the architecture parameters are optimized to minimize both the natural loss and the adversarial loss utilizing the proposed multi-objective adversarial training method, so that the searched neural architectures are both accurate and robust. We evaluate the proposed algorithm under natural data and various adversarial attacks, which reveals the superiority of the proposed method in terms of both accurate and robust architectures. We also conclude that accurate and robust neural architectures tend to deploy very different structures near the input and the output, which has great practical significance on both hand-crafting and automatically designing of accurate and robust neural architectures.