Reviewerly/exHarmony huggingface dataset:
SplitGNN: Spectral Graph Neural Network for Fraud Detection against Heterophily

Fraudsters in the real world frequently add more legitimate links while concealing their direct ones with other fraudsters, leading to heterophily in fraud graphs, which is a problem that most GNN-based techniques are not built to solve. Several works have been proposed to tackle the issue from the spatial domain. However, researches on addressing the heterophily problem in the spectral domain are still limited due to a lack of understanding of spectral energy distribution in graphs with heterophily. In this paper, we analyze the spectral distribution with different heterophily degrees and observe that the heterophily of fraud nodes leads to the spectral energy moving from low-frequency to high-frequency. Further, we verify that splitting graphs using heterophilic and homophilic edges can obtain more significant expressions of signals in different frequency bands. The observation drives us to propose the spectral graph neural network, SplitGNN, to capture signals for fraud detection against heterophily. SplitGNN uses an edge classifier to split the original graph and adopts flexible band-pass graph filters to learn representations. Extensive experiments on real-world datasets demonstrate the effectiveness of our proposed method. The code and data are available at https://github.com/Split-GNN/SplitGNN.
Metapath-Guided Data-Augmentation For Knowledge Graphs

Knowledge graph (KG) embedding techniques use relationships between entities to learn low-dimensional representations of entities and relations. The traditional KG embedding techniques (such as TransE and DistMult) estimate these embeddings using the observed KG triplets and differ in their triplet scoring loss functions. As these models only use the observed triplets to estimate the embeddings, they are prone to suffer through data sparsity that usually occurs in the real-world knowledge graphs, i.e., the lack of enough triplets per entity. In this paper, we propose an efficient method to augment the triplets to address the problem of data sparsity. We use random walks to create additional triplets, such that the relations carried by these introduced triplets correspond to the metapath (sequence of underlying relations) induced by the random walks. We also provide approaches to accurately and efficiently choose the informative metapaths from the possible set of metapaths. The proposed augmentation approaches can be used with any KG embedding approach out of the box. Experimental results on benchmarks show the advantages of the proposed approach.
TOAK: A Topology-oriented Attack Strategy for Degrading User Identity Linkage in Cross-network Learning

Privacy concerns on social networks have received extensive attention in recent years. The task of user identity linkage (UIL), which aims to identify corresponding users across different social networks, poses a threat to privacy if applied unethically. Sensitive user information would be inferred with cross-network identity linkages. A feasible solution to this issue is to design an adversarial strategy that degrades the matching performance of UIL models. Nevertheless, most of the current adversarial attacks on graphs are tailored towards models working within a single network, failing to account for the challenges presented by cross-network learning tasks such as UIL. Also, in real-world scenarios, the adversarial strategy against UIL has more constraints as service providers can only add perturbations to their own networks. To tackle these challenges, this paper proposes a novel poisoning strategy to prevent nodes in a target network from being linked to other networks by UIL algorithms. Specifically, the UIL problem is formalized in the kernelized topology consistency perspective, and the objective is formulated as maximizing the structural variations in the target network before and after modifications. To achieve this, a novel graph kernel is defined based on earth mover's distance (EMD) in the edge-embedding space. In terms of efficiency, a fast attack strategy is proposed using greedy searching and a lower bound approximation of EMD. Results on three real-world datasets demonstrate that the proposed method outperforms six baselines and reaches a balance between effectiveness and imperceptibility while being efficient.
Promoting Diversity in Mixed Complex Cooperative and Competitive Multi-Agent Environment

This paper introduces a new approach for promoting diversity of behavior in complex multi-agent environments that pose three challenges: 1) competition or collaboration among agents of diverse types, 2) the need for complex multi-agent coordination, which makes it challenging to achieve risky cooperation strategies, and 3) a large number of agents in the environment, leading to increased complexity when considering agent-to-agent relationships. To address the first two challenges, we leverage Reward Randomization in combination with Bayesian Optimization to train agents to exhibit diverse strategic behaviors, thereby mitigating the issue of risky cooperation. To address the challenge of learning in a large number of agents, we utilize MAPPO with parameter sharing to enhance learning efficiency. Experimental results demonstrate that within this multi-agent environment, agents can effectively learn multiple visually distinct behaviors, and the incorporation of these two techniques significantly improves agents' performance.
A Robust Backward Compatibility Metric for Model Retraining

Model retraining and updating are essential processes in AI applications. However, during updates, there is a potential for performance degradation, in which the overall performance improves, but local performance deteriorates. This study proposes a backward compatibility metric that focuses on the compatibility of local predictive performance. The score of the proposed metric increases if the accuracy over the conditional distribution for each input is higher than before. Furthermore, we propose a model retraining method based on the proposed metric. Due to the use of the conditional distribution, our metric and retraining method are robust against label noises, while existing sample-based backward compatibility metrics are often affected by noise. We perform a theoretical analysis of our method and derive an upper bound for the generalization error. Numerical experiments demonstrate that our retraining method enhances compatibility while achieving equal or better trade-offs in overall performance compared to existing methods.
Differential Privacy in HyperNetworks for Personalized Federated Learning

Federated learning (FL) is a framework for collaborative learning among users through a coordinating server. A recent HyperNetwork-based personalized FL framework, called HyperNetFL, is used to generate local models using personalized descriptors optimized for each user independently. However, HyperNetFL introduces unknown privacy risks. This paper introduces a novel approach to preserve user-level differential privacy, dubbed User-level DP, by providing formal privacy protection for data owners in training a HyperNetFL model. To achieve that, our proposed algorithm, called UDP-Alg, optimizes the trade-off between privacy loss and model utility by tightening sensitivity bounds. An intensive evaluation using benchmark datasets shows that our proposed UDP-Alg significantly improves privacy protection at a modest cost in utility.
Unified Generative &amp; Dense Retrieval for Query Rewriting in Sponsored Search

Sponsored search is a key revenue source for search engines, where advertisers bid on keywords to target users or search queries of interest. However, finding relevant keywords for a given query is challenging due to the large and dynamic keyword space, ambiguous user/advertiser intents, and diverse possible topics and languages. In this work, we present a comprehensive comparison between two paradigms for online query rewriting: Generative (NLG) and Dense Retrieval (DR) methods. We observe that both methods offer complementary benefits that are additive. As a result, we show that around 40% of the high-quality keywords retrieved by the two approaches are unique and not retrieved by the other. To leverage the strengths of both methods, we propose CLOVER-Unity, a novel approach that unifies generative and dense retrieval methods in one single model. Through offline experiments, we show that the NLG and DR components of CLOVER-Unity consistently outperform individually trained NLG and DR models on public and internal benchmarks. Furthermore, we show that CLOVER-Unity achieves 9.8% higher good keyword density than the ensemble of two separate DR and NLG models while reducing computational costs by almost half. We conduct extensive online A/B experiments on Microsoft Bing in 140+ countries and achieve improved user engagement, with an average increase in total clicks by 0.89% and increased revenue by 1.27%. We also share our practical lessons and optimization tricks for deploying such unified models in production.
Exposing Model Theft: A Robust and Transferable Watermark for Thwarting Model Extraction Attacks

The increasing prevalence of Deep Neural Networks (DNNs) in cloud-based services has led to their widespread use through various APIs. However, recent studies reveal the susceptibility of these public APIs to model extraction attacks, where adversaries attempt to create a local duplicate of the private model using data and API-generated predictions. Existing defense methods often involve perturbing prediction distributions to hinder an attacker's training goals, inadvertently affecting API utility. In this study, we extend the concept of digital watermarking to protect DNNs' APIs. We suggest embedding a watermark into the safeguarded APIs; thus, any model attempting to copy will inherently carry the watermark, allowing the defender to verify any suspicious models. We propose a simple yet effective framework to increase watermark transferability. By requiring the model to memorize the preset watermarks in the final decision layers, we significantly enhance the transferability of watermarks. Comprehensive experiments show that our proposed framework not only successfully watermarks APIs but also maintains their utility.
Simulating Student Interactions with Two-stage Imitation Learning for Intelligent Educational Systems

The fundamental task of intelligent educational systems is to offer adaptive learning services to students, such as exercise recommendations and computerized adaptive testing. However, optimizing required models in these systems would always encounter the collection difficulty of high-quality interaction data in practice. Therefore, establishing a student simulator is of great value since it can generate valid interactions to help optimize models. Existing advances have achieved success but generally suffer from exposure bias and overlook long-term intentions. To tackle these problems, we propose a novel Direct-Adversarial Imitation Student Simulator (DAISim) by formulating it as a Markov Decision Process (MDP), which unifies the workflow of the simulator in training and generating to alleviate the exposure bias and single-step optimization problems. To construct the intentions underlying the complex student interactions, we first propose a direct imitation strategy to mimic the interactions with a simple reward function. Then, we propose an adversarial imitation strategy to learn a rational distribution with the reward given by a parameterized discriminator. Furthermore, we optimize the discriminator in adversarial imitation in a pairwise manner, and the theoretical analysis shows that the pairwise discriminator would improve the generation quality. We conduct extensive experiments on real-world datasets, where the results demonstrate that our DAISim can simulate high-quality student interactions whose distribution is close to real distribution and can promote several downstream services.
A Semi-Supervised Anomaly Network Traffic Detection Framework via Multimodal Traffic Information Fusion

Anomaly traffic detection is a crucial issue in the cyber-security field. Previously, many researchers regarded anomaly traffic detection as a supervised classification problem. However, in real scenarios, anomaly network traffic is unpredictable, dynamically changing and difficult to collect. To address these limitations, we employ anomaly detection setting to propose a novel semi-supervised anomaly network traffic detection framework. It only learns features of normal samples during the training phase. Our framework utilizes low-pass filtering to extract multi-scale low-frequency information from 2-D traffic image. Furthermore, we design a two-stage fusion scheme to incorporate information from original and multi-scale low-frequency traffic image modalities. We conduct experiments on two public datasets: ISCX Tor-nonTor and USTC-TFC2016. The experimental results show that our method outperforms current state-of-the-art anomaly detection methods.
Sequential Text-based Knowledge Update with Self-Supervised Learning for Generative Language Models

This work proposes a new natural language processing (NLP) task to tackle the issue of multi-round, sequential text-based knowledge update. The study introduces a hybrid learning architecture and a novel self-supervised training strategy to enable generative language models to consolidate knowledge in the same way as humans. A dataset was also created for evaluation and results showed the effectiveness of our methodology. Experimental results confirm the superiority of the proposed approach over existing models and large language models (LLMs). The proposed task and model framework have the potential to significantly improve the automation of knowledge organization, making text-based knowledge an increasingly crucial resource for powerful LLMs to perform various tasks for humans.
STGIN: Spatial-Temporal Graph Interaction Network for Large-scale POI Recommendation

In Location-Based Services, Point-Of-Interest(POI) recommendation plays a crucial role in both user experience and business opportunities. Graph neural networks have been proven effective in providing personalized POI recommendation services. However, there are still two critical challenges. First, existing graph models attempt to capture users' diversified interests through a unified graph, which limits their ability to express interests in various spatial-temporal contexts. Second, the efficiency limitations of graph construction and graph sampling in large-scale systems make it difficult to adapt quickly to new real-time interests. To tackle the above challenges, we propose a novel Spatial-Temporal Graph Interaction Network. Specifically, we construct subgraphs of spatial, temporal, spatial-temporal, and global views respectively to precisely characterize the user's interests in various contexts. In addition, we design an industry-friendly framework to track the user's latest interests. Extensive experiments on the real-world dataset show that our method outperforms state-of-the-art models. This work has been successfully deployed in a large e-commerce platform, delivering a 1.1% CTR and 6.3% RPM improvement.
Manipulating Out-Domain Uncertainty Estimation in Deep Neural Networks via Targeted Clean-Label Poisoning

Robust out-domain uncertainty estimation has gained growing attention for its capacity of providing adversary-resistant uncertainty estimates on out-domain samples. However, existing work on robust uncertainty estimation mainly focuses on evasion attacks that happen during test time. The threat of poisoning attacks against uncertainty models is largely unexplored. Compared to evasion attacks, poisoning attacks do not necessarily modify test data, and therefore, would be more practical in real-world applications. In this work, we systematically investigate the robustness of state-of-the-art uncertainty estimation algorithms against data poisoning attacks, with the ultimate objective of developing robust uncertainty training methods. In particular, we focus on attacking the out-domain uncertainty estimation. Under the proposed attack, the training process of models is affected. A fake high-confidence region is established around the targeted out-domain sample, which originally would have been rejected by the model due to low confidence. More fatally, our attack is clean-label and targeted: it leaves the poisoned data with clean labels and attacks a specific targeted test sample without degrading the overall model performance. We evaluate the proposed attack on several image benchmark datasets and a real-world application of COVID-19 misinformation detection. The extensive experimental results on different tasks suggest that the state-of-the-art uncertainty estimation methods could be extremely vulnerable and easily corrupted by our proposed attack.
Knowledge Graph Error Detection with Hierarchical Path Structure

Knowledge graphs (KGs) play a pivotal role in AI-related applications. In order to construct or continuously enrich KGs, automatic knowledge construction and update mechanisms are usually utilized, which inevitably bring in plenty of noise, and noise would degrade the performance of downstream applications. Existing KG error detection methods utilize the embeddings of entities and relations, or directly leverage the paths between entities to test the plausibility of triples, while ignore the valuable hierarchical information contained in the paths between entities. Indeed, the paths between a pair of entities conform to a hierarchical structure. Specifically, there may be a number of paths between two entities, and each path is comprised of several relations. The hierarchical structure is able to provide precious information, and is beneficial to leverage the path information in a fine-grained manner. To this end, in this paper, we propose a novel model named KG error detection with HiErarchical pAth stRucture (HEAR for short). Particularly, for a given triple, HEAR first learns path representations with the relations contained in the path, then integrates all path representations, and at last predicts the plausibility of the triple. Finally, we extensively validate the superiority of HEAR against various state-of-the-art baselines.
Spans, Not Tokens: A Span-Centric Model for Multi-Span Reading Comprehension

Many questions should be answered by not a single answer but a set of multiple answers. This emerging Multi-Span Reading Comprehension (MSRC) task requires extracting multiple non-contiguous spans from a given context to answer a question. Existing methods extend conventional single-span models to predict the positions of the start and end tokens of answer spans, or predict the beginning-inside-outside tag of each token. Such token-centric paradigms can hardly capture dependencies among span-level answers which are critical to MSRC. In this paper, we propose SpanQualifier, a span-centric scheme where spans, as opposed to tokens, are directly represented and scored to qualify as answers. Explicit span representations enable their interaction which exploits their dependencies to enhance representations. Experiments on three MSRC datasets demonstrate the effectiveness of our span-centric scheme and show that SpanQualifier achieves state-of-the-art results.
Workshop On Large Language Models' Interpretability and Trustworthiness (LLMIT)

Large language models (LLMs), when scaled from millions to billions of parameters, have been demonstrated to exhibit the so-called 'emergence' effect, in that they are not only able to produce semantically correct and coherent text, but are also able to adapt themselves surprisingly well with small changes in contexts supplied as inputs (commonly called prompts). Despite producing semantically coherent and potentially relevant text for a given context, LLMs are vulnerable to yield incorrect information. This misinformation generation, or the so-called hallucination problem of an LLM, gets worse when an adversary manipulates the prompts to their own advantage, e.g., generating false propaganda to disrupt communal harmony, generating false information to trap consumers with target consumables etc. Not only does the consumption of an LLM-generated hallucinated content by humans pose societal threats, such misinformation, when used as prompts, may lead to detrimental effects for in-context learning (also known as few-shot prompt learning). With reference to the above-mentioned problems of LLM usage, we argue that it is necessary to foster research on topics related to not only identifying misinformation from LLM-generated content, but also to mitigate the propagation effects of this generated misinformation on downstream predictive tasks thus leading to more robust and effective leveraging in-context learning.
LAMM: Language Aware Active Learning for Multilingual Models

In industrial settings, it is often necessary to achieve language-level accuracy targets. For example, Amazon business teams need to build multilingual product classifiers that operate accurately in all European languages. It is unacceptable for the accuracy of product classification to meet the target in one language (e.g, English), while falling below the target in other languages (e.g, Portuguese). To fix such issues, we propose Language Aware Active Learning for Multilingual Models (LAMM), an active learning strategy that enables a classifier to learn from a small amount of labeled data in a targeted manner to improve the accuracy of Low-resource languages (LRLs) with limited amounts of data for model training. Our empirical results on two open-source datasets and two proprietary product classification datasets demonstrate that LAMM is able to improve the LRL performance by 4%--11% when compared to strong baselines.
SMEF: Social-aware Multi-dimensional Edge Features-based Graph Representation Learning for Recommendation

Exploring user-item interaction cues is crucial for the performance of recommender systems. Explicit investigation of interaction cues is made possible by using graph-based models, where each user-item relationship is described by an edge, and the introduction of user-user social network. While existing graph-based recommendation methods use only a single-value edge to define the relationship between a pair of user and item, which limits the ability to represent complex user-item interactions. Furthermore, some social recommendation methods overlook the heterogeneous user behavior patterns in social and interaction relationships, resulting in the suboptimal performance of existing systems. In this paper, we propose a novel Social-aware Multi-dimensional Edge Feature-based Graph Representation Learning method, called SMEF. It represents all users and items as a graph and deep learns a multi-dimensional edge feature to explicitly describe the task-specific relationships of each user-item pair. Specifically, the proposed SMEF focuses on two distinct user behavior patterns toward social friends and interactive items, which explore the underlying heterogeneous relationship cues within them. This way, the learned multi-dimensional edge features encode user information from both social and interaction aspects. The proposed SMEF is a plug-and-play module that can be combined with different recommendation frameworks and Graph Neural Networks (GNNs) backbones to generate high quality user representations. The experimental results achieved on three publicly accessible datasets show that our SMEF-based method outperforms strong baselines.
Black-box Adversarial Attacks against Dense Retrieval Models: A Multi-view Contrastive Learning Method

Neural ranking models (NRMs) and dense retrieval (DR) models have given rise to substantial improvements in overall retrieval performance. In addition to their effectiveness, and motivated by the proven lack of robustness of deep learning-based approaches in other areas, there is growing interest in the robustness of deep learning-based approaches to the core retrieval problem. Adversarial attack methods that have so far been developed mainly focus on attacking NRMs, with very little attention being paid to the robustness of DR models.