Graph-structured data is ubiquitous in today's connected world, driving extensive research in graph analysis. Graph Neural Networks (GNNs) have shown great success in this field, leading to growing interest in developing fair GNNs for critical applications. However, most existing fair GNNs focus on statistical fairness notions, which may be insufficient when dealing with statistical anomalies. Hence, motivated by the causal theory, there has been growing attention to mitigating root causes of unfairness utilizing graph counterfactuals. Unfortunately, existing methods for generating graph counterfactuals invariably require the sensitive attribute. Nevertheless, in many real-world applications, it is usually infeasible to obtain sensitive attributes due to privacy or legal issues, which challenge existing methods. In this paper, we propose a framework named Fairwos (improving Fairness withQut sensitive attributes). In particular, we first propose a mechanism to generate pseudo-sensitive attributes to remedy the problem of missing sensitive attributes, and then design a strategy for finding graph counterfactuals from the real dataset. To train fair GNNs, we propose a method to ensure that the embeddings from the original data are consistent with those from the graph counterfactuals, and dynamically adjust the weight of each pseudo-sensitive attribute to balance its contribution to fairness and utility. Furthermore, we theoretically demonstrate that minimizing the relation between these pseudo-sensitive attributes and the prediction can enable the fairness of GNNs. Experimental results on six real-world datasets show that our approach outperforms state-of-the-art methods in balancing utility and fairness.

As Facial Expression Recognition (FER) systems become increasingly integrated into daily life, ensuring fairness in decision-making is crucial, rather than focusing solely on improving recognition performance. FER systems need to find a trade-off between performance and fairness in order to avoid bias to subgroups while ensuring utility. To address this issue, various methods have been proposed at the data and algorithmic levels. However, these studies mainly focus on the unfairness of demographic attributes, and the bias of expression class remains largely unexplored. In this study, we attempt a novel strategy for applying class-incremental learning (class-IL) to mitigate expression class bias. Furthermore, we propose a fair model based on the characteristic of class-IL, called Incremental Expression Balance Network (IEBN). IEBN mitigates this class bias by adjusting the data distribution of different expressions and extracting critical features with an attention mechanism. Finally, experiments on the RAF-DB and AffectNet datasets show that IEBN outperforms other methods in terms of fairness and trade-offs between fairness and performance.

Eliminating bias from data representations is crucial to ensure fairness in recommendation. Existing studies primarily focus on weakening the correlation between data representations and sensitive attributes, yet may inadvertently steer the user representations toward another potential bias direction of the target attribute. Furthermore, they often overlook the impact of user preferences on capturing sensitive information, incurring inadequate bias elimination. In this paper, we propose a Fair Counterfactual Representations (FairCoRe) learning framework, which aims to ensure the neutrality of representations among all bias directions. Firstly, we intervene on sensitive attributes to construct a counterfactual scenario. Then, two opposing attribute prediction tasks are respectively performed in ground-truth and counterfactual scenarios to encode sensitive information along different bias directions. Secondly, we design a bias-aware enhancement learning method that quantifies the respective correlation of user preferences and sensitive attributes to enhance sensitive information encoding. Finally, we introduce two mutual information optimization methods that optimize the representations to capture users' interests and disentangle sensitive factors. Moreover, we propose an attribute neutralization strategy that refines the learned representations, ensuring sensitive attribute neutrality. Extensive experiments demonstrate that our method achieves the optimal fairness and competitive accuracy compared to state-of-the-art methods. The source code is available at: https://github.com/FairCoRe2024/FairCoRe.

Next POI (Point-of-Interest) recommendation aims to forecast users’ future movements based on their historical check-in trajectories, holding significant value in location-based services. Existing methods address trajectory data sparsity by integrating rich auxiliary information or using spatial-temporal knowledge graphs (STKGs), showing promising results. Yet, they face two main challenges: i) Due to the difficulty of transforming structured trajectory data into trajectory text describing users’ spatial-temporal mobility, the powerful reasoning ability of pre-trained language models is rarely explored to enhance recommendation performance. ii) Methods based on STKG can introduce external knowledge inconsistent with user preferences, leading to the knowledge noise generated hampering the accuracy of recommendations. To this end, we propose a novel approach called STKG-PLM that integratesSTKGcontrastive learning andprompt pre-trainedlanguagemodel (PLM) to enhance the next POI recommendation. Specifically, we design a spatial-temporal trajectory prompt template that transforms structured trajectories into text corpus based on STKG, serving as the input of PLM to understand the movement pattern of users from coarse-grained and fine-grained perspectives. Additionally, we propose an STKG contrastive learning framework to mitigate the introduced knowledge noise. Extensive experiments on three real-world datasets demonstrate that STKG-PLM exhibits notable performance improvements over the state-of-the-art baseline methods.

Federated Recommender Systems (FedRecs) have evolved as a privacy-preserving paradigm that facilitates distributed training of personalized recommenders without sharing user data. However, FedRecs are known to be susceptible to poisoning attacks by malicious users, who aim at promoting or demoting the exposure of target items through sending malicious updates to the central server. Meanwhile, the distribution of recommendation performance among users, called as performance fairness, could be exacerbated, which is one of the major concerns of trustworthy FedRecs. This paper proposes a novel attack method, Generative Adversarial Network (GAN)-Based Collusive Poisoning Attack (GCPA). To implement GCPA, we create a GAN-based fake user synthesis strategy that mimics behaviors and preferences of real users to generate fake users. Furthermore, we design a collusion-based fairness attack strategy that changes the exposure of items to undermine fairness. To maximize the impact on the distribution of recommendation performance, we develop an adaptive clustering algorithm to identify a subset of items that significantly contribute to the uneven distribution of recommendation performance through collusion. Extensive experiments on two datasets show that GCPA effectively increase the exposure of target items while undermining the performance fairness of FedRecs. In addition, GCPA also has strong resistance to four defense methods. Meanwhile, we provide a heuristic defense method based on gradient direction and similarity against collusive poisoning attack on FedRecs.

Multi-domain fake news detection aims to identify whether various news from different domains is real or fake and has become urgent and important. However, existing methods are dedicated to improving the overall performance of fake news detection, ignoring the fact that unbalanced data leads to disparate treatment for different domains, i.e., the domain bias problem. To solve this problem, we propose the Dual-Teacher De-biasing Distillation framework (DTDBD) to mitigate bias across different domains. Following the knowledge distillation methods, DTDBD adopts a teacher-student structure, where pre-trained large teachers instruct a student model. In particular, the DTDBD consists of an unbiased teacher and a clean teacher that jointly guide the student model in mitigating domain bias and maintaining performance. For the unbiased teacher, we introduce an adversarial de-biasing distillation loss to instruct the student model in learning unbiased domain knowledge. For the clean teacher, we design domain knowledge distillation loss, which effectively incentivizes the student model to focus on representing domain features while maintaining performance. Moreover, we present a momentum-based dynamic adjustment algorithm to trade off the effects of two teachers. Extensive experiments on Chinese and English datasets show that the proposed method substantially outperforms the state-of-the-art baseline methods in terms of bias metrics while guaranteeing competitive performance11Our codes are available at https://github.com/ningljy/DTDBD.

Community search has become especially important in graph analysis task, which aims to identify latent members of a particular community from a few given nodes. Most of the existing efforts in community search focus on exploring the community structure with a single scale in which the given nodes are located. Despite promising results, the following two insights are often neglected. First, node attributes provide rich and highly related auxiliary information apart from network interactions for characterizing the node properties. Attributes may indicate the community assignment of a node with very few links, which would be difficult to determine from the network structure alone. Second, the multiresolution community affords latent information to depict the hierarchical relation of the network and ensure that one of them is closest to the real one. It is essential for users to understand the underlying structure of the network and explore the community with strong structure and attribute cohesiveness at disparate scales. These aspects motivate us to develop a new community search framework called Multiresolution Local Spectral Attributed Community Search (MLSACS). Specifically, inspired by the local modularity, graph wavelets, and scaling functions, we propose a new Multiresolution Local modularity (MLQ) based on a reconstructed node attribute graph. Furthermore, to detect local communities with cohesive structures and attributes at different scales, a sparse indicator vector is developed based on MLQ by solving a linear programming problem. Extensive experimental results on both synthetic and real-world attributed graphs have demonstrated the detected communities are meaningful and the scale can be changed reasonably.

Quantifying similarities among human diseases is crucial to enhance our understanding of disease biology. Deep learning efforts have been devoted to quantifying disease similarity by integrating multi-view data sources from disparate biological data. However, disease data are often sparse, leading to suboptimal representation of disease given biological entity relationships and labeled disease data are not adequately modeled. In this paper, we propose an effective Synergistic disease Similarity measurement model called SynerSim. SynerSim possesses two key components: a hierarchical biological entity relation perception module to capture disease features from various biological entities, and a disease association capturing module based on signed random walk to model precious disease data. Additionally, SynerSim leverages dual granularity contrastive learning to enhance the representation of diverse biological entities, owing to the ability to enable the synergistic supervision of diseases represented by both homogeneous and heterogeneous information. Experimental results demonstrate that SynerSim achieves outstanding performance in the disease similarity measurement.

Polarized Communities Search (PCS) aims to identify query-dependent communities where positive links predominantly connect nodes within each community, while negative links primarily connect nodes across different communities. Existing solutions primarily focus on modeling network topology, disregarding the crucial factor of node attributes. However, it is non-trivial to incorporate node attributes into PCS. In this paper, we propose a novel method called CO-guided RAndom walk in attributed signed networks (CORA) for PCS. Our approach involves constructing an attribute-based signed network to represent the auxiliary relations between nodes. We introduce a weight assignment mechanism to assess the reliability of edges in the signed network. Then, we design a co-guided random walk scheme that operates on two signed networks to model the connections between network topology and node attributes, thereby enhancing the search outcomes. Finally, we identify polarized communities using the Rayleigh quotient in the signed network. Extensive experiments conducted on three public datasets demonstrate the superior performance of CORA compared to state-of-the-art baselines for polarized communities search.

Recently, multi-behavior recommendation has become a hot topic in the field of recommendation systems. Yet, existing methods still face challenges in effectively representing multi-behavior semantic information from the following perspectives: (i) Previous works’ heavy reliance on a unified embedding for modeling all behavior interaction graphs hindered accuratemining of fine-grained user preference semantics across multiple behaviors. (ii) Existing multi-behavior contrastive learning (CL) tasks fail to capture the dependency of user preferring to items under different behaviors, thereby constrains the model’s ability in characterizing the personalized features of users/items. (iii) The rich semantic information in the knowledge graph is not fully leveraged. To address the above challenges, we design a Contrastive Learning-based Multi-behavior Recommendation with Semantic Knowledge Enhancement (CLMRS) framework, which consists of two encoding modules with CL tasks and a joint learning module. Specifically, in the multi-behavior meta-network encoding module, we propose a novel behavior-supervised graph convolutional encoder to fully mine the user preference semantics in each behavior. Meanwhile, in the semantic knowledge enhanced encoding module, we use a knowledge graph to provide more robust embeddings for items. Finally, we integrate the user/item embeddings learned by the two encoding modules into a comprehensive semantic vector through the joint learning module, which is used for the final prediction of potential users. Extensive experiments on four real-world datasets indicate that CLMRS consistently outperforms various state-of-the-art recommendation methods. Our model code is available at https://github.com/yuwenxuan3197/CLMRS.

Heterogeneous information networks (HINs) are widely used in recommender system research due to their ability to model complex auxiliary information beyond historical interactions to alleviate data sparsity problem. Existing HIN-based recommendation studies have achieved great success via performing graph convolution operators between pairs of nodes on predefined metapath induced graphs, but they have the following major limitations. First, existing heterogeneous network construction strategies tend to exploit item attributes while failing to effectively model user relations. In addition, previous HIN-based recommendation models mainly convert heterogeneous graph into homogeneous graphs by defining metapaths ignoring the complicated relation dependency involved on the metapath. To tackle these limitations, we propose a novel recommendation model with two-way metapath encoder for top-N recommendation, which models metapath similarity and sequence relation dependency in HIN to learn node representations. Specifically, our model first learns the initial node representation through a pre-training module, and then identifies potential friends and item relations based on their similarity to construct a unified HIN. We then develop the two-way encoder module with similarity encoder and instance encoder to capture the similarity collaborative signals and relational dependency on different metapaths. Finally, the representations on different meta-paths are aggregated through the attention fusion layer to yield rich representations. Extensive experiments on three real datasets demonstrate the effectiveness of our method.

Session-based recommendation (SBR) aims to predict the next item based on anonymous behavior session, which has become increasingly essential in various online services. Prior efforts mainly focus on modeling user preference based on the current session. Although some of them have been proven effective, they fail to address two main challenges in SBR. First, SBR suffers more from the problem of data sparsity due to the very limited user–item interactions, and hence it cannot sufficiently capture complicated item dependency relationships. Second, most of the user-item interaction sequences may be with noisy preference signals due to the uncertainty of user's behaviors, and it is difficult to distill high-quality item for recommendation. In this study, we propose a novel SBR model that exploits Cross-session information for Knowledge-aware Session-based Recommendation (CKSR) to address these two issues. Specifically, cross-session graph and knowledge graph are combined to model a cross-session knowledge graph, based on which a knowledge-aware attention mechanism is performed to capture the complicated transition pattern among interacted items. Each session is then represented as the composition of the global preference and the current interest of that session. Moreover, we leverage the similar sessions for the target session to establish a similar session referral circle and apply an influence coupler to judge the significance of different session referrals. An attentive network is designed to distill session preferences from its unique session referral circle. It dynamically extracts high-quality item from noisy session. Experiments on two benchmark data sets demonstrate that CKSR outperforms the state-of-the-art methods consistently.

Pathfinding becomes an important component in many real-world scenarios, such as popular warehouse systems and autonomous aircraft towing vehicles. With the development of reinforcement learning (RL) especially in the context of asynchronous advantage actor-critic (A3C), pathfinding is undergoing a revolution in terms of efficient parallel learning. Similar to other artificial intelligence-based applications, A3C-based pathfinding is also threatened by the adversarial attack. In this paper, we are the first to study the adversarial attack to A3C, that can unexpectedly wake up longtime retraining mechanism until successful pathfinding. We also discover an attack example generation to launch the attack based on gradient band, in which only one baffle of extremely few unit lengths can successfully perform the attack. Experiments with detailed analysis are conducted to show a high attack success rate of 95% with an average baffle length of 2.95. We also discuss defense suggestions leveraging the insights from our analysis.

The increased accessibility of urban sensor data and the popularity of social network applications is enabling the discovery of crowd mobility and personal communication patterns. However, studying the egocentric relationships of an individual can be very challenging because available data may refer to direct contacts, such as phone calls between individuals, or indirect contacts, such as paired location presence. In this article, we develop methods to integrate three facets extracted from heterogeneous urban data (timelines, calls, and locations) through a progressive visual reasoning and inspection scheme. Our approach uses a detect-and-filter scheme such that, prior to visual refinement and analysis, a coarse detection is performed to extract the target individual and construct the timeline of the target. It then detects spatio-temporal co-occurrences or call-based contacts to develop the egocentric network of the individual. The filtering stage is enhanced with a line-based visual reasoning interface that facilitates a flexible and comprehensive investigation of egocentric relationships and connections in terms of time, space, and social networks. The integrated system, RelationLines, is demonstrated using a dataset that contains taxi GPS data, cell-base mobility data, mobile calling data, microblog data, and point-of-interest (POI) data from a city with millions of citizens. We examine the effectiveness and efficiency of our system with three case studies and user review.