OpenRaiser/Intern-Atlas huggingface dataset:
Temporal context-aware representation learning for question routing
Authors: Xuchao Zhang, Wei Cheng, Bo Zong, Yuncong Chen, Jianwu Xu, Ding Li, Haifeng Chen
Venue: Conference WSDM 2020
Year: 2020

Question routing (QR) aims at recommending newly posted questions to the potential answerers who are most likely to answer the questions. The existing approaches that learn users' expertise from their past question-answering activities usually suffer from challenges in two aspects: 1) multi-faceted expertise and 2) temporal dynamics in the answering behavior. This paper proposes a novel temporal context-aware model in multiple granularities of temporal dynamics that concurrently address the above challenges. Specifically, the temporal context-aware attention characterizes the answerer's multi-faceted expertise in terms of the questions' semantic and temporal information simultaneously. Moreover, the design of the multi-shift and multi-resolution module enables our model to handle temporal impact on different time granularities. Extensive experiments on six datasets from different domains demonstrate that the proposed model significantly outperforms competitive baseline models.
A classification-based approach to question routing in community question answering
Authors: Tom Chao Zhou, Michael R. Lyu, Irwin King
Venue: Conference WWW 2012
Year: 2012

Community-based Question and Answering (CQA) services have brought users to a new era of knowledge dissemination by allowing users to ask questions and to answer other users' questions. However, due to the fast increasing of posted questions and the lack of an effective way to find interesting questions, there is a serious gap between posted questions and potential answerers. This gap may degrade a CQA service's performance as well as reduce users' loyalty to the system. To bridge the gap, we present a new approach to Question Routing, which aims at routing questions to participants who are likely to provide answers. We consider the problem of question routing as a classification task, and develop a variety of local and global features which capture different aspects of questions, users, and their relations. Our experimental results obtained from an evaluation over the Yahoo!~Answers dataset demonstrate high feasibility of question routing. We also perform a systematical comparison on how different types of features contribute to the final results and show that question-user relationship features play a key role in improving the overall performance.
Parallel SimRank computation on large graphs with iterative aggregation
Authors: Guoming He, Haijun Feng, Cuiping Li, Hong Chen
Venue: Conference KDD 2010
Year: 2010

Recently there has been a lot of interest in graph-based analysis. One of the most important aspects of graph-based analysis is to measure similarity between nodes in a graph. SimRank is a simple and influential measure of this kind, based on a solid graph theoretical model. However, existing methods on SimRank computation suffer from two limitations: 1) the computing cost can be very high in practice; and 2) they can only be applied on static graphs. In this paper, we exploit the inherent parallelism and high memory bandwidth of graphics processing units (GPU) to accelerate the computation of SimRank on large graphs. Furthermore, based on the observation that SimRank is essentially a first-order Markov Chain, we propose to utilize the iterative aggregation techniques for uncoupling Markov chains to compute SimRank scores in parallel for large graphs. The iterative aggregation method can be applied on dynamic graphs. Moreover, it can handle not only the link-updating problem but also the node-updating problem. Extensive experiments on synthetic and real data sets verify that the proposed methods are efficient and effective.
Agenda: Robust personalized PageRanks in evolving graphs
Authors: Dingheng Mo, Siqiang Luo
Venue: Conference CIKM 2021
Year: 2021

Given a source node s and a target node t in a graph G, the Personalized PageRank (PPR) from s to t is the probability of a random walk starting from s terminates at t. PPR is a classic measure of the relevance among different nodes in a graph, and has been applied in numerous real-world systems. However, existing techniques for PPR queries are not robust to dynamic real-world graphs, which typically have different evolving speeds. Their performance is significantly degraded either at a lower graph evolving rate (e.g., much more queries than updates) or a higher rate. To address the above deficiencies, we propose Agenda to efficiently process, with strong approximation guarantees, the single-source PPR (SSPPR) queries on dynamically evolving graphs with various evolving speeds. Compared with previous methods, Agenda has significantly better workload robustness, while ensuring the same result accuracy. Agenda also has theoretically-guaranteed small query and update costs. Experiments on up to billion-edge scale graphs show that Agenda significantly outperforms state-of-the-art methods for various query/update workloads, while maintaining better or comparable approximation accuracies.
An evaluation of SimRank and Personalized PageRank to build a recommender system for the Web of Data
Authors: Phuong T. Nguyen, Paolo Tomeo, Tommaso Di Noia, Eugenio Di Sciascio
Venue: Conference WWW 2015
Year: 2015

The Web of Data is the natural evolution of the World Wide Web from a set of interlinked documents to a set of interlinked entities. It is a graph of information resources interconnected by semantic relations, thereby yielding the name Linked Data. The proliferation of Linked Data is for sure an opportunity to create a new family of data-intensive applications such as recommender systems. In particular, since content-based recommender systems base on the notion of similarity between items, the selection of the right graph-based similarity metric is of paramount importance to build an effective recommendation engine. In this paper, we review two existing metrics, SimRank and PageRank, and investigate their suitability and performance for computing similarity between resources in RDF graphs and investigate their usage to feed a content-based recommender system. Finally, we conduct experimental evaluations on a dataset for musical artists and bands recommendations thus comparing our results with two other content-based baselines measuring their performance with precision and recall, catalog coverage, items distribution and novelty metrics.
Aspectmmkg: A multi-modal knowledge graph with aspect-aware entities
Authors: Jingdan Zhang, Jiaan Wang, Xiaodan Wang, Zhixu Li, Yanghua Xiao
Venue: Conference CIKM 2023
Year: 2023

Multi-modal knowledge graphs (MMKGs) combine different modal data (e.g., text and image) for a comprehensive understanding of entities. Despite the recent progress of large-scale MMKGs, existing MMKGs neglect the multi-aspect nature of entities, limiting the ability to comprehend entities from various perspectives. In this paper, we construct AspectMMKG, the first MMKG with aspect-related images by matching images to different entity aspects. Specifically, we collect aspect-related images from a knowledge base, and further extract aspect-related sentences from the knowledge base as queries to retrieve a large number of aspect-related images via an online image search engine. Finally, AspectMMKG contains 2,380 entities, 18,139 entity aspects, and 645,383 aspect-related images. We demonstrate the usability of AspectMMKG in entity aspect linking (EAL) downstream task and show that previous EAL models achieve a new state-of-the-art performance with the help of AspectMMKG. To facilitate the research on aspect-related MMKG, we further propose an aspect-related image retrieval (AIR) model, that aims to correct and expand aspect-related images in AspectMMKG. We train an AIR model to learn the relationship between entity image and entity aspect-related images by incorporating entity image, aspect, and aspect image information. Experimental results indicate that the AIR model could retrieve suitable images for a given entity w.r.t different aspects.
Topic-aware source locating in social networks
Authors: Wenyu Zang, Chuan Zhou, Li Guo, Peng Zhang
Venue: Conference WWW 2015
Year: 2015

In this paper we address the problem of source locating in social networks from a topic modeling perspective. From the observation that the topic factor can help infer the propagation paths, we propose a topic-aware source locating method based on topic analysis of propagation items and participants. We evaluate our algorithm on both generated and real-world datasets. The experimental results show significant improvement over existing popular methods.
Socially-aware self-supervised tri-training for recommendation
Authors: Junliang Yu, Hongzhi Yin, Min Gao, Xin Xia, Xiangliang Zhang, Nguyen Quoc Viet Hung
Venue: Conference KDD 2021
Year: 2021

Self-supervised learning (SSL), which can automatically generate ground-truth samples from raw data, holds vast potential to improve recommender systems. Most existing SSL-based methods perturb the raw data graph with uniform node/edge dropout to generate new data views and then conduct the self-discrimination based contrastive learning over different views to learn generalizable representations. Under this scheme, only a bijective mapping is built between nodes in two different views, which means that the self-supervision signals from other nodes are being neglected. Due to the widely observed homophily in recommender systems, we argue that the supervisory signals from other nodes are also highly likely to benefit the representation learning for recommendation. To capture these signals, a general socially-aware SSL framework that integrates tri-training is proposed in this paper. Technically, our framework first augments the user data views with the user social information. And then under the regime of tri-training for multi-view encoding, the framework builds three graph encoders (one for recommendation) upon the augmented views and iteratively improves each encoder with self-supervision signals from other users, generated by the other two encoders. Since the tri-training operates on the augmented views of the same data sources for self-supervision signals, we name it self-supervised tri-training. Extensive experiments on multiple real-world datasets consistently validate the effectiveness of the self-supervised tri-training framework for improving recommendation. The code is released at https://github.com/Coder-Yu/QRec.
Price does matter! modeling price and interest preferences in session-based recommendation
Authors: Xiaokun Zhang, Bo Xu, Liang Yang, Chenliang Li, Fenglong Ma, Haifeng Liu, Hongfei Lin
Venue: Conference SIGIR 2022
Year: 2022

Session-based recommendation aims to predict items that an anonymous user would like to purchase based on her short behavior sequence. The current approaches towards session-based recommendation only focus on modeling users' interest preferences, while they all ignore a key attribute of an item, i.e., the price. Many marketing studies have shown that the price factor significantly influences users' behaviors and the purchase decisions of users are determined by both price and interest preferences simultaneously. However, it is nontrivial to incorporate price preferences for session-based recommendation. Firstly, it is hard to handle heterogeneous information from various features of items to capture users' price preferences. Secondly, it is difficult to model the complex relations between price and interest preferences in determining user choices. To address the above challenges, we propose a novel method Co-guided Heterogeneous Hypergraph Network (CoHHN) for session-based recommendation. Towards the first challenge, we devise a heterogeneous hypergraph to represent heterogeneous information and rich relations among them. A dual-channel aggregating mechanism is then designed to aggregate various information in the heterogeneous hypergraph. After that, we extract users' price preferences and interest preferences via attention layers. As to the second challenge, a co-guided learning scheme is designed to model the relations between price and interest preferences and enhance the learning of each other. Finally, we predict user actions based on item features and users' price and interest preferences. Extensive experiments on three real-world datasets demonstrate the effectiveness of the proposed CoHHN. Further analysis reveals the significance of price for session-based recommendation.
Knowledge-infused contrastive learning for urban imagery-based socioeconomic prediction
Authors: Yu Liu, Xin Zhang, Jingtao Ding, Yanxin Xi, Yong Li
Venue: Conference WWW 2023
Year: 2023

Monitoring sustainable development goals requires accurate and timely socioeconomic statistics, while ubiquitous and frequently-updated urban imagery in web like satellite/street view images has emerged as an important source for socioeconomic prediction. Especially, recent studies turn to self-supervised contrastive learning with manually designed similarity metrics for urban imagery representation learning and further socioeconomic prediction, which however suffers from effectiveness and robustness issues. To address such issues, in this paper, we propose a Knowledge-infused Contrastive Learning (KnowCL) model for urban imagery-based socioeconomic prediction. Specifically, we firstly introduce knowledge graph (KG) to effectively model the urban knowledge in spatiality, mobility, etc., and then build neural network based encoders to learn representations of an urban image in associated semantic and visual spaces, respectively. Finally, we design a cross-modality based contrastive learning framework with a novel image-KG contrastive loss, which maximizes the mutual information between semantic and visual representations for knowledge infusion. Extensive experiments of applying the learnt visual representations for socioeconomic prediction on three datasets demonstrate the superior performance of KnowCL with over 30\% improvements on $R^2$ compared with baselines. Especially, our proposed KnowCL model can apply to both satellite and street imagery with both effectiveness and transferability achieved, which provides insights into urban imagery-based socioeconomic prediction.
Cross-modality mutual learning for enhancing smart contract vulnerability detection on bytecode
Authors: Peng Qian, Zhenguang Liu, Yifang Yin, Qinming He
Venue: Conference WWW 2023
Year: 2023

Over the past couple of years, smart contracts have been plagued by multifarious vulnerabilities, which have led to catastrophic financial losses. Their security issues, therefore, have drawn intense attention. As countermeasures, a family of tools has been developed to identify vulnerabilities in smart contracts at the source-code level. Unfortunately, only a small fraction of smart contracts is currently open-sourced. Another spectrum of work is presented to deal with pure bytecode, but most such efforts still suffer from relatively low performance due to the inherent difficulty in restoring abundant semantics in the source code from the bytecode. This paper proposes a novel cross-modality mutual learning framework for enhancing smart contract vulnerability detection on bytecode. Specifically, we engage in two networks, a student network as the primary network and a teacher network as the auxiliary network. takes two modalities, i.e., source code and its corresponding bytecode as inputs, while is fed with only bytecode. By learning from , is trained to infer the missed source code embeddings and combine both modalities to approach precise vulnerability detection. To further facilitate mutual learning between and , we present a cross-modality mutual learning loss and two transfer losses. As a side contribution, we construct and release a labeled smart contract dataset that concerns four types of common vulnerabilities. Experimental results show that our method significantly surpasses state-of-the-art approaches.
Modeling extreme events in time series prediction
Authors: Daizong Ding, Mi Zhang, Xudong Pan, Min Yang, Xiangnan He
Venue: Conference KDD 2019
Year: 2019

Time series prediction is an intensively studied topic in data mining. In spite of the considerable improvements, recent deep learning-based methods overlook the existence of extreme events, which result in weak performance when applying them to real time series. Extreme events are rare and random, but do play a critical role in many real applications, such as the forecasting of financial crisis and natural disasters. In this paper, we explore the central theme of improving the ability of deep learning on modeling extreme events for time series prediction. Through the lens of formal analysis, we first find that the weakness of deep learning methods roots in the conventional form of quadratic loss. To address this issue, we take inspirations from the Extreme Value Theory, developing a new form of loss called Extreme Value Loss (EVL) for detecting the future occurrence of extreme events. Furthermore, we propose to employ Memory Network in order to memorize extreme events in historical records.By incorporating EVL with an adapted memory network module, we achieve an end-to-end framework for time series prediction with extreme events. Through extensive experiments on synthetic data and two real datasets of stock and climate, we empirically validate the effectiveness of our framework. Besides, we also provide a proper choice for hyper-parameters in our proposed framework by conducting several additional experiments.
Compressed interaction graph based framework for multi-behavior recommendation
Authors: Wei Guo, Chang Meng, Enming Yuan, Zhicheng He, Huifeng Guo, Yingxue Zhang, Bo Chen, Yaochen Hu, Ruiming Tang, Xiu Li, Rui Zhang
Venue: Conference WWW 2023
Year: 2023

Multi-types of user behavior data (e.g., clicking, adding to cart, and purchasing) are recorded in most real-world recommendation scenarios, which can help to learn users' multi-faceted preferences. However, it is challenging to explore multi-behavior data due to the unbalanced data distribution and sparse target behavior, which lead to the inadequate modeling of high-order relations when treating multi-behavior data ''as features'' and gradient conflict in multitask learning when treating multi-behavior data ''as labels''. In this paper, we propose CIGF, a Compressed Interaction Graph based Framework, to overcome the above limitations. Specifically, we design a novel Compressed Interaction Graph Convolution Network (CIGCN) to model instance-level high-order relations explicitly. To alleviate the potential gradient conflict when treating multi-behavior data ''as labels'', we propose a Multi-Expert with Separate Input (MESI) network with separate input on the top of CIGCN for multi-task learning. Comprehensive experiments on three large-scale real-world datasets demonstrate the superiority of CIGF. Ablation studies and in-depth analysis further validate the effectiveness of our proposed model in capturing high-order relations and alleviating gradient conflict. The source code and datasets are available at https://github.com/MC-CV/CIGF.
Graph embedding discriminant analysis on grassmannian manifolds for improved image set matching
Authors: Mehrtash Tafazzoli Harandi, Conrad Sanderson, Sareh Abolahrari Shirazi, Brian C. Lovell
Venue: Conference CVPR 2011
Year: 2011

A convenient way of dealing with image sets is to represent them as points on Grassmannian manifolds. While several recent studies explored the applicability of discriminant analysis on such manifolds, the conventional formalism of discriminant analysis suffers from not considering the local structure of the data. We propose a discriminant analysis approach on Grassmannian manifolds, based on a graph-embedding framework. We show that by introducing within-class and between-class similarity graphs to characterise intra-class compactness and inter-class separability, the geometrical structure of data can be exploited. Experiments on several image datasets (PIE, BANCA, MoBo, ETH-80) show that the proposed algorithm obtains considerable improvements in discrimination accuracy, in comparison to three recent methods: Grassmann Discriminant Analysis (GDA), Kernel GDA, and the kernel version of Affine Hull Image Set Distance. We further propose a Grassmannian kernel, based on canonical correlation between subspaces, which can increase discrimination accuracy when used in combination with previous Grassmannian kernels.
Meta matrix factorization for federated rating predictions
Authors: Yujie Lin 0001, Pengjie Ren, Zhumin Chen, Zhaochun Ren, Dongxiao Yu, Jun Ma 0001, Maarten de Rijke, Xiuzhen Cheng 0001
Venue: Conference SIGIR 2020
Year: 2020

With distinct privacy protection advantages, federated recommendation is becoming increasingly feasible to store data locally in devices and federally train recommender models. However, previous work on federated recommender systems does not take full account of the limitations of storage, RAM, energy and communication bandwidth in the mobile environment. Their model scales are too big to run easily in mobile devices. Moreover, existing federated recommenders need to fine-tune recommendation models in each device, which makes them hard to effectively exploit collaborative filtering (CF) information among users/devices.
Privaterec: Differentially private model training and online serving for federated news recommendation
Authors: Ruixuan Liu, Yang Cao 0011, Yanlin Wang 0001, Lingjuan Lyu, Yun Chen 0007, Hong Chen 0001
Venue: Conference KDD 2023
Year: 2023

Federated recommendation can potentially alleviate the privacy concerns in collecting sensitive and personal data for training personalized recommendation systems. However, it suffers from a low recommendation quality when a local serving is inapplicable due to the local resource limitation and the data privacy of querying clients is required in online serving. Furthermore, a theoretically private solution in both the training and serving of federated recommendation is essential but still lacking. Naively applying differential privacy (DP) to the two stages in federated recommendation would fail to achieve a satisfactory trade-off between privacy and utility due to the high-dimensional characteristics of model gradients and hidden representations. In this work, we propose a federated news recommendation method for achieving better utility in model training and online serving under a DP guarantee. We first clarify the DP definition over behavior data for each round in the pipeline of federated recommendation systems. Next, we propose a privacy-preserving online serving mechanism under this definition based on the idea of decomposing user embeddings with public basic vectors and perturbing the lower-dimensional combination coefficients. We apply a random behavior padding mechanism to reduce the required noise intensity for better utility. Besides, we design a federated recommendation model training method, which can generate effective and public basic vectors for serving while providing DP for training participants. We avoid the dimension-dependent noise for large models via label permutation and differentially private attention modules. Experiments on real-world news recommendation datasets validate that our method achieves superior utility under a DP guarantee in both training and serving of federated news recommendations.