空间优化问题（SOP）的特征是管理决策变量，目标和/或约束功能的空间关系。在本文中，我们关注一种称为空间分区的特定类型的SOP，这是一个组合问题，这是由于存在离散空间单元。精确的优化方法不会随着问题的大小而扩展，尤其是在可行的时间限制内。这促使我们开发基于人群的元启发式学来解决此类SOP。但是，这些基于人群的方法采用的搜索操作员主要是为实参与者连续优化问题而设计的。为了使这些方法适应SOP，我们将域知识应用于设计空间感知的搜索操作员，以在保留空间约束的同时有效地通过离散搜索空间进行有效搜索。为此，我们提出了一种简单而有效的算法，称为基于群的空间模因算法（空间），并在学校（RE）区域问题上进行测试。对现实世界数据集进行了详细的实验研究，以评估空间的性能。此外，进行消融研究以了解空间各个组成部分的作用。此外，我们讨论空间〜如何在现实生活计划过程及其对不同方案的适用性并激发未来的研究方向有帮助。

由于其在线社交网络上的广泛应用，影响力最大化（IM）在过去几十年中引起了广泛关注。当前的IM研究缺乏对种子如何产生影响效应的人类理解的解释，从而降低了现有解决方案的可信度，尽管它们适用。由于IM的复杂性，目前的大多数研究都集中在估计一阶扩散能力上，并且经常考虑从不同种子分散的流量之间的相互作用。这项研究使用SOBOL指数，这是基于方差的灵敏度分析的基石，可以分解对单个种子及其相互作用的影响效果。 SOBOL指数是针对IM上下文量身定制的，通过将种子选择作为二进制变量进行建模。这种说明方法普遍适用于所有网络类型，IM技术和扩散模型。基于解释方法，提出了一个称为Sobolim的一般框架，以通过过度选择节点，然后是消除策略来提高IM研究的性能。关于合成和现实世界图的实验表明，对影响效应的解释可以可靠地识别各种网络和IM方法之间种子之间的关键高阶相互作用。在经验上，Sobolim在有效性和效率上具有优势。

最近，越来越多的研究人员，尤其是在政治重新划分领域的研究人员，提出了基于抽样的技术，以从各个地区计划的广阔空间中制定一部分计划。这些技术已被美国法院和独立委员会越来越多地采用，作为确定游击队的工具。在这些最近的发展的促进下，我们开发了一系列基于翻转建议的学校边界的类似抽样技术。请注意，此处的翻转提案是指单个任务的区域计划的更改。这些基于抽样的技术具有双重目的。它们可以用作基线，用于比较基于本地搜索的重新划分算法。此外，这些技术可以帮助推断出可以进一步用于开发有效重新分配方法的问题特征。关于学校重新划分问题，我们从经验上谈到了这两个方面。

建模传染病传播的时空性质可以提供有用的直觉，以了解疾病传播的时变方面，并且在人们的行动模式中观察到的潜在的复杂空间依赖性。此外，可以利用县级多相关时间序列信息，以便在单个时间序列进行预测。添加到这一挑战是实时数据常常偏离单向高斯分布假设，并且可以显示一些复杂的混合模式。由此激励，我们开发了一种基于深度学习的时间序列模型，用于自动回归混合密度动态扩散网络（ARM3DNet）的概率预测，其认为人们的移动性和疾病在动态定向图上传播。实现高斯混合模型层以考虑从多个相关时间序列学习的实时数据的多模式性质。我们展示了我们的模型，当由于动态协变量特征和混合成分的最佳组合培训时，可以超越传统的统计和深度学习模式，以预测美国县级的Covid-19死亡和案例的数量。

Deep learning models can achieve high accuracy when trained on large amounts of labeled data. However, real-world scenarios often involve several challenges: Training data may become available in installments, may originate from multiple different domains, and may not contain labels for training. Certain settings, for instance medical applications, often involve further restrictions that prohibit retention of previously seen data due to privacy regulations. In this work, to address such challenges, we study unsupervised segmentation in continual learning scenarios that involve domain shift. To that end, we introduce GarDA (Generative Appearance Replay for continual Domain Adaptation), a generative-replay based approach that can adapt a segmentation model sequentially to new domains with unlabeled data. In contrast to single-step unsupervised domain adaptation (UDA), continual adaptation to a sequence of domains enables leveraging and consolidation of information from multiple domains. Unlike previous approaches in incremental UDA, our method does not require access to previously seen data, making it applicable in many practical scenarios. We evaluate GarDA on two datasets with different organs and modalities, where it substantially outperforms existing techniques.

The development of social media user stance detection and bot detection methods rely heavily on large-scale and high-quality benchmarks. However, in addition to low annotation quality, existing benchmarks generally have incomplete user relationships, suppressing graph-based account detection research. To address these issues, we propose a Multi-Relational Graph-Based Twitter Account Detection Benchmark (MGTAB), the first standardized graph-based benchmark for account detection. To our knowledge, MGTAB was built based on the largest original data in the field, with over 1.55 million users and 130 million tweets. MGTAB contains 10,199 expert-annotated users and 7 types of relationships, ensuring high-quality annotation and diversified relations. In MGTAB, we extracted the 20 user property features with the greatest information gain and user tweet features as the user features. In addition, we performed a thorough evaluation of MGTAB and other public datasets. Our experiments found that graph-based approaches are generally more effective than feature-based approaches and perform better when introducing multiple relations. By analyzing experiment results, we identify effective approaches for account detection and provide potential future research directions in this field. Our benchmark and standardized evaluation procedures are freely available at: https://github.com/GraphDetec/MGTAB.

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.

We propose a distributionally robust return-risk model for Markov decision processes (MDPs) under risk and reward ambiguity. The proposed model optimizes the weighted average of mean and percentile performances, and it covers the distributionally robust MDPs and the distributionally robust chance-constrained MDPs (both under reward ambiguity) as special cases. By considering that the unknown reward distribution lies in a Wasserstein ambiguity set, we derive the tractable reformulation for our model. In particular, we show that that the return-risk model can also account for risk from uncertain transition kernel when one only seeks deterministic policies, and that a distributionally robust MDP under the percentile criterion can be reformulated as its nominal counterpart at an adjusted risk level. A scalable first-order algorithm is designed to solve large-scale problems, and we demonstrate the advantages of our proposed model and algorithm through numerical experiments.

Witnessing the impressive achievements of pre-training techniques on large-scale data in the field of computer vision and natural language processing, we wonder whether this idea could be adapted in a grab-and-go spirit, and mitigate the sample inefficiency problem for visuomotor driving. Given the highly dynamic and variant nature of the input, the visuomotor driving task inherently lacks view and translation invariance, and the visual input contains massive irrelevant information for decision making, resulting in predominant pre-training approaches from general vision less suitable for the autonomous driving task. To this end, we propose PPGeo (Policy Pre-training via Geometric modeling), an intuitive and straightforward fully self-supervised framework curated for the policy pretraining in visuomotor driving. We aim at learning policy representations as a powerful abstraction by modeling 3D geometric scenes on large-scale unlabeled and uncalibrated YouTube driving videos. The proposed PPGeo is performed in two stages to support effective self-supervised training. In the first stage, the geometric modeling framework generates pose and depth predictions simultaneously, with two consecutive frames as input. In the second stage, the visual encoder learns driving policy representation by predicting the future ego-motion and optimizing with the photometric error based on current visual observation only. As such, the pre-trained visual encoder is equipped with rich driving policy related representations and thereby competent for multiple visuomotor driving tasks. Extensive experiments covering a wide span of challenging scenarios have demonstrated the superiority of our proposed approach, where improvements range from 2% to even over 100% with very limited data. Code and models will be available at https://github.com/OpenDriveLab/PPGeo.