节流是当今在线广告市场中最受欢迎的预算控制方法之一。当一个受预算受限的广告商雇用节流功能时，她可以在广告平台建议出价后选择是否参加拍卖。本文重点介绍了从理论观点重复的第二价格拍卖中的动态预算节流过程。潜在问题的一个重要特征是，广告商不知道进入市场时竞争最高的出价。为了模拟消除这种不确定性的困难，我们考虑了两种不同的信息结构。广告商可以通过全信息反馈获得每轮竞争最高的投标。同时，通过部分信息反馈，广告商只能在她参加的拍卖中获得最高竞争的出价。我们提出了OGD-CB算法，该算法涉及在线广告查询面临的同时分配学习和收入优化。在这两种情况下，我们都证明该算法保证了$ O（\ sqrt {t \ log t}）$遗憾，概率$ 1- o（1/t）$相对于流体自适应节流基准。通过证明$ \ omega（\ sqrt {t}）$的下限在最小的后悔中，即使是最佳的最佳选择，我们就建立了算法的近乎最佳性。最后，我们将节流的最佳流体最佳与起搏相提并论，这是另一种广泛采用的预算控制方法。这些基准的数值关系使我们对不同的在线算法进行预算管理的比较有了进一步的见解。

高光谱图像的聚类是一个基本而具有挑战性的任务。最近的高光谱图像聚类的发展已经从浅模型演变为深度，并且在许多基准数据集中实现了有希望的效果。然而，它们较差的可扩展性，稳健性和泛化能力，主要是由离线聚类方案引起的，极大地将其应用限制为大型超光谱数据。为了规避这些问题，我们基于自我监督学习呈现了一个可扩展的深度在线聚类模型，名为Spectral-Spatial对比聚类（SSCC）。具体地，我们利用了由簇号的一维的投影头组成的对称双神经网络，以从光谱空间增强池进行双重对比度学习。我们通过隐式鼓励在群集内相似度和群集冗余之间来定义目标函数。由此产生的方法通过批量优化以端到端的方式培训，使其在大规模数据中具有稳健性，并导致未经看明数据的良好概括能力。三个高光谱图像基准的广泛实验证明了我们的方法的有效性，并表明我们通过大型边缘推进最先进的方法。

本文提出了FLGC，这是一个简单但有效的全线性图形卷积网络，用于半监督和无人监督的学习。基于计算具有解耦步骤的全局最优闭合液解决方案而不是使用梯度下降，而不是使用梯度下降。我们展示（1）FLGC强大的是处理图形结构化数据和常规数据，（2）具有闭合形式解决方案的训练图卷积模型提高了计算效率而不会降低性能，而（3）FLGC作为自然概括非欧几里德域的经典线性模型，例如Ridge回归和子空间聚类。此外，我们通过引入初始剩余策略来实现半监督的FLGC和无监督的FLGC，使FLGC能够聚集长距离邻域并减轻过平滑。我们将我们的半监督和无人监督的FLGC与各种分类和聚类基准的许多最先进的方法进行比较，表明建议的FLGC模型在准确性，鲁棒性和学习效率方面始终如一地优于先前的方法。我们的FLGC的核心代码在https://github.com/angrycai/flgc下发布。

Recent investigations on rotation invariance for 3D point clouds have been devoted to devising rotation-invariant feature descriptors or learning canonical spaces where objects are semantically aligned. Examinations of learning frameworks for invariance have seldom been looked into. In this work, we review rotation invariance in terms of point cloud registration and propose an effective framework for rotation invariance learning via three sequential stages, namely rotation-invariant shape encoding, aligned feature integration, and deep feature registration. We first encode shape descriptors constructed with respect to reference frames defined over different scales, e.g., local patches and global topology, to generate rotation-invariant latent shape codes. Within the integration stage, we propose Aligned Integration Transformer to produce a discriminative feature representation by integrating point-wise self- and cross-relations established within the shape codes. Meanwhile, we adopt rigid transformations between reference frames to align the shape codes for feature consistency across different scales. Finally, the deep integrated feature is registered to both rotation-invariant shape codes to maximize feature similarities, such that rotation invariance of the integrated feature is preserved and shared semantic information is implicitly extracted from shape codes. Experimental results on 3D shape classification, part segmentation, and retrieval tasks prove the feasibility of our work. Our project page is released at: https://rotation3d.github.io/.

With the attention mechanism, transformers achieve significant empirical successes. Despite the intuitive understanding that transformers perform relational inference over long sequences to produce desirable representations, we lack a rigorous theory on how the attention mechanism achieves it. In particular, several intriguing questions remain open: (a) What makes a desirable representation? (b) How does the attention mechanism infer the desirable representation within the forward pass? (c) How does a pretraining procedure learn to infer the desirable representation through the backward pass? We observe that, as is the case in BERT and ViT, input tokens are often exchangeable since they already include positional encodings. The notion of exchangeability induces a latent variable model that is invariant to input sizes, which enables our theoretical analysis. - To answer (a) on representation, we establish the existence of a sufficient and minimal representation of input tokens. In particular, such a representation instantiates the posterior distribution of the latent variable given input tokens, which plays a central role in predicting output labels and solving downstream tasks. - To answer (b) on inference, we prove that attention with the desired parameter infers the latent posterior up to an approximation error, which is decreasing in input sizes. In detail, we quantify how attention approximates the conditional mean of the value given the key, which characterizes how it performs relational inference over long sequences. - To answer (c) on learning, we prove that both supervised and self-supervised objectives allow empirical risk minimization to learn the desired parameter up to a generalization error, which is independent of input sizes. Particularly, in the self-supervised setting, we identify a condition number that is pivotal to solving downstream tasks.

In the new era of personalization, learning the heterogeneous treatment effect (HTE) becomes an inevitable trend with numerous applications. Yet, most existing HTE estimation methods focus on independently and identically distributed observations and cannot handle the non-stationarity and temporal dependency in the common panel data setting. The treatment evaluators developed for panel data, on the other hand, typically ignore the individualized information. To fill the gap, in this paper, we initialize the study of HTE estimation in panel data. Under different assumptions for HTE identifiability, we propose the corresponding heterogeneous one-side and two-side synthetic learner, namely H1SL and H2SL, by leveraging the state-of-the-art HTE estimator for non-panel data and generalizing the synthetic control method that allows flexible data generating process. We establish the convergence rates of the proposed estimators. The superior performance of the proposed methods over existing ones is demonstrated by extensive numerical studies.

Generalizability to unseen forgery types is crucial for face forgery detectors. Recent works have made significant progress in terms of generalization by synthetic forgery data augmentation. In this work, we explore another path for improving the generalization. Our goal is to reduce the features that are easy to learn in the training phase, so as to reduce the risk of overfitting on specific forgery types. Specifically, in our method, a teacher network takes as input the face images and generates an attention map of the deep features by a diverse multihead attention ViT. The attention map is used to guide a student network to focus on the low-attended features by reducing the highly-attended deep features. A deep feature mixup strategy is also proposed to synthesize forgeries in the feature domain. Experiments demonstrate that, without data augmentation, our method is able to achieve promising performances on unseen forgeries and highly compressed data.

In this work, we investigate improving the generalizability of GAN-generated image detectors by performing data augmentation in the fingerprint domain. Specifically, we first separate the fingerprints and contents of the GAN-generated images using an autoencoder based GAN fingerprint extractor, followed by random perturbations of the fingerprints. Then the original fingerprints are substituted with the perturbed fingerprints and added to the original contents, to produce images that are visually invariant but with distinct fingerprints. The perturbed images can successfully imitate images generated by different GANs to improve the generalization of the detectors, which is demonstrated by the spectra visualization. To our knowledge, we are the first to conduct data augmentation in the fingerprint domain. Our work explores a novel prospect that is distinct from previous works on spatial and frequency domain augmentation. Extensive cross-GAN experiments demonstrate the effectiveness of our method compared to the state-of-the-art methods in detecting fake images generated by unknown GANs.

The high feature dimensionality is a challenge in music emotion recognition. There is no common consensus on a relation between audio features and emotion. The MER system uses all available features to recognize emotion; however, this is not an optimal solution since it contains irrelevant data acting as noise. In this paper, we introduce a feature selection approach to eliminate redundant features for MER. We created a Selected Feature Set (SFS) based on the feature selection algorithm (FSA) and benchmarked it by training with two models, Support Vector Regression (SVR) and Random Forest (RF) and comparing them against with using the Complete Feature Set (CFS). The result indicates that the performance of MER has improved for both Random Forest (RF) and Support Vector Regression (SVR) models by using SFS. We found using FSA can improve performance in all scenarios, and it has potential benefits for model efficiency and stability for MER task.

A general, {\em rectangular} kernel matrix may be defined as $K_{ij} = \kappa(x_i,y_j)$ where $\kappa(x,y)$ is a kernel function and where $X=\{x_i\}_{i=1}^m$ and $Y=\{y_i\}_{i=1}^n$ are two sets of points. In this paper, we seek a low-rank approximation to a kernel matrix where the sets of points $X$ and $Y$ are large and are not well-separated (e.g., the points in $X$ and $Y$ may be ``intermingled''). Such rectangular kernel matrices may arise, for example, in Gaussian process regression where $X$ corresponds to the training data and $Y$ corresponds to the test data. In this case, the points are often high-dimensional. Since the point sets are large, we must exploit the fact that the matrix arises from a kernel function, and avoid forming the matrix, and thus ruling out most algebraic techniques. In particular, we seek methods that can scale linearly, i.e., with computational complexity $O(m)$ or $O(n)$ for a fixed accuracy or rank. The main idea in this paper is to {\em geometrically} select appropriate subsets of points to construct a low rank approximation. An analysis in this paper guides how this selection should be performed.