There is some recent research interest in algorithmic fairness for biased data. There are a variety of pre-, in-, and post-processing methods designed for this problem. However, these methods are exclusively targeting data unfairness and algorithmic unfairness. In this paper, we propose a novel intra-processing method to broaden the application scenario of fairness methods, which can simultaneously address the two bias sources. Since training modern deep models from scratch is expensive due to the enormous training data and the complicated structures, we propose an augmentation and fine-tuning framework. First, we design an adversarial attack to generate weighted samples disentangled with the protected attribute. Next, we identify the fair sub-structure in the biased model and fine-tune the model via weight reactivation. At last, we provide an optional joint training scheme for the augmentation and the fine-tuning. Our method can be combined with a variety of fairness measures. We benchmark our method and some related baselines to show the advantage and the scalability. Experimental results on several standard datasets demonstrate that our approach can effectively learn fair augmentation and achieve superior results to the state-of-the-art baselines. Our method also generalizes well to different types of data.

Graph neural networks (GNN) are powerful tools in many web research problems. However, existing GNNs are not fully suitable for many real-world web applications. For example, over-smoothing may affect personalized recommendations and the lack of an explanation for the GNN prediction hind the understanding of many business scenarios. To address these problems, in this paper, we propose a new second-order continuous GNN which naturally avoids over-smoothing and enjoys better interpretability. There is some research interest in continuous graph neural networks inspired by the recent success of neural ordinary differential equations (ODEs). However, there are some remaining problems w.r.t. the prevailing first-order continuous GNN frameworks. Firstly, augmenting node features is an essential, however heuristic step for the numerical stability of current frameworks; secondly, first-order methods characterize a diffusion process, in which the over-smoothing effect w.r.t. node representations are intrinsic; and thirdly, there are some difficulties to integrate the topology of graphs into the ODEs. Therefore, we propose a framework employing second-order graph neural networks, which usually learn a less stiff transformation than the first-order counterpart. Our method can also be viewed as a coupled first-order model, which is easy to implement. We propose a semi-model-agnostic method based on our model to enhance the prediction explanation using high-order information. We construct an analog between continuous GNNs and some famous partial differential equations and discuss some properties of the first and second-order models. Extensive experiments demonstrate the effectiveness of our proposed method, and the results outperform related baselines.

The self-supervised graph representation learning has achieved much success in recent web based research and applications, such as recommendation system, social networks, and anomaly detection. However, existing works suffer from two problems. Firstly, in social networks, the influential neighbors are important, but the overwhelming routine in graph representation-learning utilizes the node-wise similarity metric defined on embedding vectors that cannot exactly capture the subtle local structure and the network proximity. Secondly, existing works implicitly assume a universal distribution across datasets, which presumably leads to sub-optimal models considering the potential distribution shift. To address these problems, in this paper, we learn structural embeddings in which the proximity is characterized by 1-Wasserstein distance. We propose a distributionally robust self-supervised graph neural network framework to learn the representations. More specifically, in our method, the embeddings are computed based on subgraphs centering at the node of interest and represent both the node of interest and its neighbors, which better preserves the local structure of nodes. To make our model end-to-end trainable, we adopt a deep implicit layer to compute the Wasserstein distance, which can be formulated as a differentiable convex optimization problem. Meanwhile, our distributionally robust formulation explicitly constrains the maximal diversity for matched queries and keys. As such, our model is insensitive to the data distributions and has better generalization abilities. Extensive experiments demonstrate that the graph encoder learned by our approach can be utilized for various downstream analyses, including node classification, graph classification, and top-k similarity search. The results show our algorithm outperforms state-of-the-art baselines, and the ablation study validates the effectiveness of our design.

In classification problems, individual fairness prevents discrimination against individuals based on protected attributes. Fairness-aware methods usually consist of two stages, first determining a fair metric concerning the similarity between different instances and then learning the fairness-aware model. However, existing works usually consider these two stages separately and only focus on improving the individual stage. Moreover, the choice of fair metric is heavily dependent on the task or dataset of interest, which requires ad-hoc domain knowledge and introduces extra difficulty into algorithm designing. As such, this discrepancy presumably leads to sub-optimal fairness-aware pipelines for different applications. In this paper, we propose to fill in the fairness learning gap between these two stages by automatically learning an effective metric integrated into the fairness of both data and classifiers. Specifically, we formulate the fairness-aware classification as a distributional robustness optimization problem based on deep metric learning and propose an effective optimization algorithm to solve it. Meanwhile, we establish the asymptotically unbiased generalization bounds for the proposed algorithm using the techniques of U-statistics. The experimental results on popular benchmark datasets demonstrate that the proposed approach achieves consistent improvement concerning several fairness assessments.