Treatment effect estimation is essential in the causal inference literature, which has attracted increasing attention in recent years. Most previous methods assume that the training and test data are drawn from the same distribution, which may not hold in practice since the effect estimators may need to be deployed across domains. Meanwhile, in real-world applications, little or no targeted treatments may be conducted in the new domain. Therefore, we focus on a more realistic scenario in this paper, where treatments and outcomes can be observed in the source domain, but the target domain only contains some unlabeled data, i.e., only features are available. In this scenario, thedistribution shift exists not only in the source data due to the selection bias between the control and treated groups, but also between the source and target data. We propose a novel direct learning framework along with the distribution adaptation and reliable scoring modules. In the distribution adaptation module, we design three specialized density ratio estimators to aid the issue of complex distribution shifts. Even so, we may face the challenge of unreliable pseudo-effects in this framework. To address that, we also design the uncertainty-based reliable scoring module as a vital support, which makes the method more reliable. The experiments are conducted on synthetic data and benchmark datasets, which demonstrate the superiority of our method.

Federated learning is a promising machine learning paradigm that enables participating clients to train models collaboratively with privacy restrictions. However, one of the most challenging problems in federated learning is that local data on the clients might come from different distributions. Such data heterogeneity among the clients might influence the performance of federated learning methods. In this paper, we propose FedACRS, an algorithm that deals with heterogeneous data by clustering clients with similar data distributions into groups and then performing federated learning within each group. FedACRS measures the similarity between the clients in every round based on the representation similarity and then adaptively discovers the clustering structure among the clients. In order to cluster the clients appropriately, we provide theoretical analysis to help determine the number of potential clusters. The results of extensive experiments in different settings demonstrate the advantage of FedACRS over the compared methods.

In this paper, we present a framework to deal with the fraud detection task with extremely few labeled frauds. We involve human intelligence in the loop in a labor-saving manner and introduce several ingenious designs to the model construction process. Namely, a rule mining module is introduced, and the learned rules will be refined with expert knowledge. The refined rules will be used to relabel the unlabeled samples and get the potential frauds. We further present a model to learn with the reliable frauds, the potential frauds, and the rest normal samples. Note that the label noise problem, class imbalance problem, and confirmation bias problem are all addressed with specific strategies when building the model. Experimental results are reported to demonstrate the effectiveness of the framework.

As the trace norm can discover low-rank structures in a matrix, it has been widely used in multi-task learning to recover the low-rank structure contained in the parameter matrix. Recently, with the emerging of big complex datasets and the popularity of deep learning techniques, tensor trace norms have been used for deep multi-task models. However, existing tensor trace norms exhibit some limitations. For example, they cannot discover all the low-rank structures in a tensor, they require users to manually specify the importance of each component in the corresponding tensor trace norm, and they only capture the linear low-rank structure. To solve the first issue, in this paper, we propose a Generalized Tensor Trace Norm (GTTN). The GTTN is defined as a convex combination of matrix trace norms of all possible tensor flattenings and hence it can discover all the possible low-rank structures. For the second issue, in the induced objective function with the GTTN, we propose four strategies to learn combination coefficients in the GTTN. Furthermore, we propose the Nonlinear GTTN (NGTTN) to capture nonlinear low-rank structure among all the tasks. Experiments on benchmark datasets demonstrate the effectiveness of the proposed GTTN and NGTTN.

The trace norm is widely used in multi-task learning as it can discover low-rank structures among tasks in terms of model parameters. Nowadays, with the emerging of big complex datasets and the popularity of deep learning techniques, tensor trace norms have been used for deep multi-task models. However, existing tensor trace norms cannot discover all the low-rank structures and they require users to determine the importance of their components manually. To solve those two issues, in this paper, we propose a Generalized Tensor Trace Norm (GTTN). The GTTN is defined as a convex combination of matrix trace norms of all possible tensor flattenings and hence it can discover all the possible low-rank structures. Based on the induced objective function with the GTTN, we can learn combination coefficients in the GTTN with several strategies. Experiments on real-world datasets demonstrate the effectiveness of the proposed GTTN.