Synthesizing electronic health records (EHR) data has become a preferred strategy to address data scarcity, improve data quality, and model fairness in healthcare. However, existing approaches for EHR data generation predominantly rely on state-of-the-art generative techniques like generative adversarial networks, variational autoencoders, and language models. These methods typically replicate input visits, resulting in inadequate modeling of temporal dependencies between visits and overlooking the generation of time information, a crucial element in EHR data. Moreover, their ability to learn visit representations is limited due to simple linear mapping functions, thus compromising generation quality. To address these limitations, we propose a novel EHR data generation model called EHRPD. It is a diffusion-based model designed to predict the next visit based on the current one while also incorporating time interval estimation. To enhance generation quality and diversity, we introduce a novel time-aware visit embedding module and a pioneering predictive denoising diffusion probabilistic model (P-DDPM). Additionally, we devise a predictive U-Net (PU-Net) to optimize P-DDPM. We conduct experiments on two public datasets and evaluate EHRPD from fidelity, privacy, and utility perspectives. The experimental results demonstrate the efficacy and utility of the proposed EHRPD in addressing the aforementioned limitations and advancing EHR data generation.

Health risk prediction aims to forecast the potential health risks that patients may face using their historical Electronic Health Records (EHR). Although several effective models have developed, data insufficiency is a key issue undermining their effectiveness. Various data generation and augmentation methods have been introduced to mitigate this issue by expanding the size of the training data set through learning underlying data distributions. However, the performance of these methods is often limited due to their task-unrelated design. To address these shortcomings, this paper introduces a novel, end-to-end diffusion-based risk prediction model, named MedDiffusion. It enhances risk prediction performance by creating synthetic patient data during training to enlarge sample space. Furthermore, MedDiffusion discerns hidden relationships between patient visits using a step-wise attention mechanism, enabling the model to automatically retain the most vital information for generating high-quality data. Experimental evaluation on four real-world medical datasets demonstrates that MedDiffusion outperforms 14 cutting-edge baselines in terms of PR-AUC, F1, and Cohen's Kappa. We also conduct ablation studies and benchmark our model against GAN-based alternatives to further validate the rationality and adaptability of our model design. Additionally, we analyze generated data to offer fresh insights into the model's interpretability. The source code is available via https://shorturl.at/aerT0.

Cross-lingual natural language understanding~(NLU) aims to train NLU models on a source language and apply the models to NLU tasks in target languages, and is a fundamental task for many cross-language applications. Most of the existing cross-lingual NLU models assume the existence of parallel corpora so that words and sentences in source and target languages could be aligned. However, the construction of such parallel corpora is expensive and sometimes infeasible. Motivated by this challenge, recent works propose data augmentation or adversarial training methods to reduce the reliance on external parallel corpora. In this paper, we propose an orthogonal and novel perspective to tackle this challenging cross-lingual NLU task (i.e., when parallel corpora are unavailable). We propose to conduct multi-task learning across different tasks for mutual performance improvement on both source and target languages. The proposed multi-task learning framework is complementary to existing studies and could be integrated with existing methods to further improve their performance on challenging cross-lingual NLU tasks.

Federated learning (FL) enables multiple clients to train models collaboratively without sharing local data, which has achieved promising results in different areas, including the Internet of Things (IoT). However, end IoT devices do not have abilities to automatically annotate their collected data, which leads to the label shortage issue at the client side. To collaboratively train an FL model, we can only use a small number of labeled data stored on the server. This is a new yet practical scenario in federated learning, i.e., labels-at-server semi-supervised federated learning (SemiFL). Although several SemiFL approaches have been proposed recently, none of them can focus on the personalization issue in their model design. IoT environments make SemiFL more challenging, as we need to take device computational constraints and communication cost into consideration simultaneously. To tackle these new challenges together, we propose a novel SemiFL framework named pFedKnow. pFedKnow generates lightweight personalized client models via neural network pruning techniques to reduce communication cost. Moreover, it incorporates pretrained large models as prior knowledge to guide the aggregation of personalized client models and further enhance the framework performance. Experiment results on both image and text datasets show that the proposed pFedKnow outperforms state-of-the-art baselines as well as reducing considerable communication cost. The source code of the proposed pFedKnow is available at https://github.com/JackqqWang/pfedknow/tree/master.

The knowledge concept prerequisites describing the dependencies are critical for fundamental tasks such as material recommendations and there are a huge amount of concepts in Massive Open Online Courses (MOOCs). Thus it is necessary to develop automatic prerequisite relation annotation methods. Recently, a few methods have shown their effectiveness in discovering knowledge concept prerequisites in Moocs automatically. However, they suffer from two common issues, i.e., knowledge concepts are not thoroughly learnt, and informative supervision sources are ignored. To overcome these issues, we propose an end-to-end framework to incorporate the rich heterogeneous information in MOOCs, including the semantic, contextual and structural information of the learning materials as well as student video watching behaviors. Such useful information is not only used to derive entity representations but also as supervision to improve the prerequisite learning task. Experimental results on two public datasets show that the proposed framework outperforms state-of-the-art baselines in terms of precision, recall and F1 values and improves up to 9% in terms of F1 metrics. Besides, ablation study demonstrates the effectiveness of the proposed framework.

Multilingual natural language understanding, which aims to comprehend multilingual documents, is an important task. Existing efforts have been focusing on the analysis of centrally stored text data, but in real practice, multilingual data is usually distributed. Federated learning is a promising paradigm to solve this problem, which trains local models with decentralized data on local clients and aggregates local models on the central server to achieve a good global model. However, existing federated learning methods assume that data are independent and identically distributed (IID), and cannot handle multilingual data, that are usually non-IID with severely skewed distributions: First, multilingual data is stored on local client devices such that there are only monolingual or bilingual data stored on each client. This makes it difficult for local models to know the information of documents in other languages. Second, the distribution over different languages could be skewed. High resource language data is much more abundant than low resource language data. The model trained on such skewed data may focus more on high resource languages but fail to consider the key information of low resource languages. To solve the aforementioned challenges of multilingual federated NLU, we propose a plug-and-play knowledge composition (KC) module, called FedKC, which exchanges knowledge among clients without sharing raw data. Specifically, we propose an effective way to calculate a consistency loss defined based on the shared knowledge across clients, which enables models trained on different clients achieve similar predictions on similar data. Leveraging this consistency loss, joint training is thus conducted on distributed data respecting the privacy constraints. We also analyze the potential risk of FedKC and provide theoretical bound to show that it is difficult to recover data from the corrupted data. We conduct extensive experiments on three public multilingual datasets for three typical NLU tasks, including paraphrase identification, question answering matching, and news classification. The experiment results show that the proposed FedKC can outperform state-of-the-art baselines on the three datasets significantly.

Federated Learning has shown great potentials for the distributed data utilization and privacy protection. Most existing federated learning approaches focus on the supervised setting, which means all the data stored in each client has labels. However, in real-world applications, the client data are impossible to be fully labeled. Thus, how to exploit the unlabeled data should be a new challenge for federated learning. Although a few studies are attempting to overcome this challenge, they may suffer from information leakage or misleading information usage problems. To tackle these issues, in this paper, we propose a novel federated semi-supervised learning method named FedTriNet, which consists of two learning phases. In the first phase, we pre-train FedTriNet using labeled data with FedAvg. In the second phase, we aim to make most of the unlabeled data to help model learning. In particular, we propose to use three networks and a dynamic quality control mechanism to generate high-quality pseudo labels for unlabeled data, which are added to the training set. Finally, FedTriNet uses the new training set to retrain the model. Experimental results on three publicly available datasets show that the proposed FedTriNet outperforms state-of-the-art baselines under both IID and Non-IID settings.

Knowledge graphs, which consist of entities and their relations, have become a popular way to store structured knowledge. Knowledge graph embedding (KGE), which derives a representation for each entity and relation, has been widely used to capture the semantics of the information in the knowledge graphs, and has demonstrated great success in many downstream applications, such as the extraction of similar entities in response to a query entity. However, existing KGE methods cannot work well on emerging knowledge graphs that are large-scale due to the constraints in storage and inference efficiency. In this paper, we propose a lightweight KGE model, LightKG, which significantly reduces storage as well as running time needed for inference. Instead of storing a continuous vector for every entity, LightKG only needs to store a few codebooks, each of which contains some codewords that correspond to the representatives among the embeddings, and the indices that correspond to the codeword selections for entities. Hence LightKG can achieve highly efficient storage. The efficiency of the downstream querying process can be significantly boosted too with the proposed LightKG model as the relevance score between the query and an entity can be efficiently calculated via a quick look-up in a table that contains the scores between the query and codewords. The storage and inference efficiency of LightKG is achieved by its novel design. LightKG is an end-to-end framework that automatically infers codebooks and codewords and generates an approximated embedding for each entity. A residual module is included in LightKG to induce the diversity among codebooks, and a continuous function is adopted to approximate codeword selection, which is non-differential. In addition, to further improve the performance of KGE, we propose a novel dynamic negative sampling method based on quantization, which can be applied to the proposed LightKG or other KGE methods. We conduct extensive experiments on five public datasets. The experiments show that LightKG is search and memory efficient with high approximate search accuracy. Also, the dynamic negative sampling can dramatically improve model performance with over 19% improvement on average.

The broad adoption of electronic health record (EHR) systems and the advances of deep learning technology have motivated the development of health risk prediction models, which mainly depend on the expressiveness and temporal modeling capacity of deep neural networks (DNNs) to improve prediction performance. Some further augment the prediction by using external knowledge, however, a great deal of EHR information inevitably loses during the knowledge mapping. In addition, prediction made by existing models usually lacks reliable interpretation, which undermines their reliability in guiding clinical decision-making. To solve these challenges, we propose MedRetriever, an effective and flexible framework that leverages unstructured medical text collected from authoritative websites to augment health risk prediction as well as to provide understandable interpretation. Besides, MedRetriever explicitly takes the target disease documents into consideration, which provide key guidance for the model to learn in a target-driven direction, i.e., from the target disease to the input EHR. To specify, MedRetriever can flexibly choose its backbone from major predictive models to learn the EHR embedding for each visit. After that, the EHR embedding and features of target disease documents are aggregated into a query by self-attention to retrieve highly relevant text segments from the medical text pool, which is stored in the dynamically updated text memory. Finally, the comprehensive EHR embedding and the text memory are used for prediction and interpretation. We evaluate MedRetriever against nine state-of-the-art approaches across three real-world EHR datasets, which consistently achieves the best performance in AUC and recall metrics and outperforms the best baseline by at least 4.8% in recall on three test datasets. Furthermore, we conduct case studies to show the easy-to-understand interpretation by MedRetriever.

Neural sequence labeling is widely adopted for many Natural Language Processing (NLP) tasks, such as Named Entity Recognition (NER) and slot tagging for dialog systems and semantic parsing. Recent advances with large-scale pre-trained language models have shown remarkable success in these tasks when fine-tuned on large amounts of task-specific labeled data. However, obtaining such large-scale labeled training data is not only costly, but also may not be feasible in many sensitive user applications due to data access and privacy constraints. This is exacerbated for sequence labeling tasks requiring such annotations at token-level. In this work, we develop techniques to address the label scarcity challenge for neural sequence labeling models. Specifically, we propose a meta self-training framework which leverages very few manually annotated labels for training neural sequence models. While self-training serves as an effective mechanism to learn from large amounts of unlabeled data via iterative knowledge exchange -- meta-learning helps in adaptive sample re-weighting to mitigate error propagation from noisy pseudo-labels. Extensive experiments on six benchmark datasets including two for massive multilingual NER and four slot tagging datasets for task-oriented dialog systems demonstrate the effectiveness of our method. With only 10 labeled examples for each class in each task, the proposed method achieves 10% improvement over state-of-the-art methods demonstrating its effectiveness for limited training labels regime.

Fake news travels at unprecedented speeds, reaches global audiences and puts users and communities at great risk via social media platforms. Deep learning based models show good performance when trained on large amounts of labeled data on events of interest, whereas the performance of models tends to degrade on other events due to domain shift. Therefore, significant challenges are posed for existing detection approaches to detect fake news on emergent events, where large-scale labeled datasets are difficult to obtain. Moreover, adding the knowledge from newly emergent events requires to build a new model from scratch or continue to fine-tune the model, which can be challenging, expensive, and unrealistic for real-world settings. In order to address those challenges, we propose an end-to-end fake news detection framework named MetaFEND, which is able to learn quickly to detect fake news on emergent events with a few verified posts. Specifically, the proposed model integrates meta-learning and neural process methods together to enjoy the benefits of these approaches. In particular, a label embedding module and a hard attention mechanism are proposed to enhance the effectiveness by handling categorical information and trimming irrelevant posts. Extensive experiments are conducted on multimedia datasets collected from Twitter and Weibo. The experimental results show our proposed MetaFEND model can detect fake news on never-seen events effectively and outperform the state-of-the-art methods.

Predicting the current learning outcome of a student based on his/her responses to previous questions is a vital task for personalized education.Deep learning based models have achieved satisfactory performance on this task as they can automatically extract meaningful signals related to student learning outcome predictions.However, these models are unable to leverage the following critical pieces of information.First, the correct choice to a question is often accompanied by a textual explanation on why this choice is correct.This explanation text contains valuable informa-

Despite the wide adoption of classification algorithms in many fields, their predictions may hurt the benefit of some people due to the ubiquitous bias over sensitive features, such as race, gender and age. To avoid biased predictions, extensive research efforts have been devoted to training fair classification models under a variety of fairness definitions. However, we observe that recent fair classification methods may still make their predictions based on sensitive features implicitly under existing fairness definitions because the non-sensitive features these models rely on still have the capabilities of predicting the values of sensitive features. To overcome this limitation, we introduce a new fairness definition named “Fairness Through Strict Unawareness” for deep neural networks (DNN), which emphasizes the unpredictability of the sensitive features by the fair classification model. Accordingly, we proposed a bi-level optimization-based approach that prevents the encoded features of a DNN classifier to rely on any sensitive information (explicitly or implicitly). We show that the proposed framework satisfies the fairness under strict unawareness condition while still maintains its prediction accuracy. Experimental results on two benchmark datasets also support this claim. Results show that the proposed framework can significantly degrade the models' ability of inferring sensitive features without sacrificing its general predictive capability.

The broad adoption of electronic health records (EHR) data and the availability of biomedical knowledge graphs (KGs) on the web have provided clinicians and researchers unprecedented resources and opportunities for conducting health risk predictions to improve healthcare quality and medical resource allocation. Existing methods have focused on improving the EHR feature representations using attention mechanisms, time-aware models, or external knowledge. However, they ignore the importance of using personalized information to make predictions. Besides, the reliability of their prediction interpretations needs to be improved since their interpretable attention scores are not explicitly reasoned from disease progression paths. In this paper, we propose MedPath to solve these challenges and augment existing risk prediction models with the ability to use personalized information and provide reliable interpretations inferring from disease progression paths. Firstly, MedPath extracts personalized knowledge graphs (PKGs) containing all possible disease progression paths from observed symptoms to target diseases from a large-scale online medical knowledge graph. Next, to augment existing EHR encoders for achieving better predictions, MedPath learns a PKG embedding by conducting multi-hop message passing from symptom nodes to target disease nodes through a graph neural network encoder. Since MedPath reasons disease progression by paths existing in PKGs, it can provide explicit explanations for the prediction by pointing out how observed symptoms can finally lead to target diseases. Experimental results on three real-world medical datasets show that MedPath is effective in improving the performance of eight state-of-the-art methods with higher F1 scores and AUCs. Our case study also demonstrates that MedPath can greatly improve the explicitness of the risk prediction interpretation.1

Recent advances in information extraction have motivated the automatic construction of huge Knowledge Graphs (KGs) by mining from large-scale text corpus. However, noisy facts are unavoidably introduced into KGs that could be caused by automatic extraction.

Outlier detection is of vital importance for various fields and applications. Existing works mainly focus on identifying outliers from underlying datasets, while how to provide sense-making explanations is largely ignored. In this paper, we propose to visualize data points in a set of scatter plots on two-dimensional (2-D) feature spaces that can provide meaningful explanations about the outlying behavior of outliers. Data are typically multidimensional and the number of 2-D combinations could be huge. Also, outliers may have diverse characteristics, and thus the global scatter plots containing all of outliers may degrade the explanation effectiveness for those outliers having idiosyncratic abnormal 2-D spaces. To address this problem, we propose a new outlier explanation approach, called LP-Explain, which tries to identify the set of best Local Pictorial explanations (defined as the scatter plots in the 2-D space of the feature pairs) that can Explain the behavior for cluster of outliers. We first define an effective measure to quantify the similarity between outliers, and then cluster outliers into different groups based on their abnormal feature pairs. We then propose to weigh the importance of feature pairs within each cluster through a multi-task learning framework to select the set of top feature pairs that best explain various outlier clusters. By adjusting a user-defined parameter indicating the “localization level”, the proposed method can attain both global and local results for the explanation of the outliers. 2-D visual explanations can be plotted for the top-weighted feature pairs of each cluster. We conduct experiments on various public datasets, which show that the proposed approach can provide more meaningful explanations about the outlying behavior in a dataset.

Can one build a knowledge graph (KG) for all products in the world? Knowledge graphs have firmly established themselves as valuable sources of information for search and question answering, and it is natural to wonder if a KG can contain information about products offered at online retail sites. There have been several successful examples of generic KGs, but organizing information about products poses many additional challenges, including sparsity and noise of structured data for products, complexity of the domain with millions of product types and thousands of attributes, heterogeneity across large number of categories, as well as large and constantly growing number of products.

Product catalogs are valuable resources for eCommerce website. In the catalog, a product is associated with multiple attributes whose values are short texts, such as product name, brand, functionality and flavor. Usually individual retailers self-report these key values, and thus the catalog information unavoidably contains noisy facts. It is very important to validate the correctness of these values in order to improve shopper experiences and enable more effective product recommendation. Due to the huge volume of products, an effective automatic validation approach is needed. In this paper, we propose to develop an automatic validation approach that verifies the correctness of textual attribute values for products. This can be formulated as a task as cross-checking a textual attribute value against product profile, which is a short textual description of the product on eCommerce website. Although existing deep neural network models have shown success in conducting cross-checking between two pieces of texts, their success has to be dependent upon a large set of quality labeled data, which are hard to obtain in this validation task: products span a variety of categories. Due to the category difference, annotation has to be done on all the categories, which is impossible to achieve in real practice.

Predicting diseases for patients is an important and practical task in healthcare informatics. Existing disease prediction models focus on common diseases, i.e., there are enough available EHR data and prior medical knowledge for analyzing them. However, those models may not work for rare disease prediction as it is extremely hard to collect enough EHR data with such diseases. To tackle these issues, in this paper, we design a novel rare disease prediction system, which not only generates EHR data but also automatically selects high-quality generated data to further improve the predictive performance. Three components are designed in the system: data generation, data selection, and prediction. In particular, we propose MaskEHR to generate diverse EHR data based on the data from patients suffering from the given diseases. To remove noise information in the generated EHR data, we further design a reinforcement learning-based data selector, called RL-Selector, which can automatically choose the high-quality generated EHR data. Finally, the prediction component is used to identify patients who will potentially suffer the given diseases. These three components work together and enhance each other. Experiments on three real healthcare datasets show that the proposed system outperforms existing approaches on rare disease prediction task.

Hypothesis generation (HG) refers to the task of mining meaningful implicit association between unlinked biomedical concepts. The majority of prior studies have focused on uncovering these implicit linkages from static snapshots of the corpus, thereby largely ignoring the temporal dynamics of medical concepts. More recently, a few initial studies attempted to overcome this issue by modelling the temporal change of concepts from natural language text. However, they still fail to leverage the evolutionary features of concepts from contemporary knowledge-bases (KB's) such as semantic lexicons and ontologies. In practice such KB's contain up-to-date information that is important to incorporate, especially, in highly evolving domains such as biomedicine. Furthermore, considering the complementary strength of these sources of information - corpus and ontology - a few natural questions arise: Can joint modelling of (co)-evolutionary dynamics from these resources aid in encoding the temporal features at a granular level? Can the mutual evolution between these intertwined resources lead to better predictive effects? To answer these questions, in this study, we present a novel HG framework that unearths the latent associations between concepts by modeling their co-evolution across complementary sources of information. More specifically, the proposed approach adopts a shared temporal matrix factorization framework that models the co-evolution of concepts across both corpus and KB. Extensive experiments on the largest available biomedical corpus validates the effectiveness of the proposed approach.

Detecting local events (e.g., protests, accidents) in real-time is an important task needed by a wide spectrum of real-world applications. In recent years, with the proliferation of social media platforms, we can access massive geo- tagged social messages, which can serve as a precious resource for timely local event detection. However, existing local event detection methods either suffer from unsatisfactory performances or need intensive annotations. These limitations make existing methods impractical for large-scale applications. Through the analysis of real-world datasets, we found that the informativeness level of social media users, which is neglected by existing work, plays a highly critical role in distilling event-related information from noisy social media contexts. Motivated by this finding, we propose an unsupervised framework, named LEDetect, to estimate the informativeness level of social media users and leverage the power of highly informative users for local event detection. Experiments on a large-scale real-world dataset show that the proposed LEDetect model can improve the performance of event detection compared with the state-of-the-art unsupervised approach. Also, we use case studies to show that the events discovered by the proposed model are of high quality and the extracted highly informative users are reasonable.

Word embeddings are finding their increasing application in a variety of biomedical Natural Language Processing (bioNLP) tasks, ranging from drug discovery to automated disease diagnosis. While these word embeddings in their entirety have shown meaningful syntactic and semantic regularities, however, the meaning of individual dimensions remains elusive. This becomes problematic both in general and particularly in sensitive domains such as bio-medicine, wherein, the interpretability of results is crucial to its widespread adoption. To address this issue, in this study, we aim to improve the interpretability of pre-trained word embeddings generated from a text corpora, and in doing so provide a systematic approach to formalize the problem. More specifically, we exploit the rich categorical knowledge present in the biomedical domain, and propose to learn a transformation matrix that transforms the input embeddings to a new space where they are both interpretable and retain their original expressive features. Experiments conducted on the largest available biomedical corpus suggests that the model is capable of performing interpretability that resembles closely to the human-level intuition.

Recent advances in attention networks have gained enormous interest in time series data mining. Various attention mechanisms are proposed to soft-select relevant timestamps from temporal data by assigning learnable attention scores. However, many real-world tasks involve complex multivariate time series that continuously measure target from multiple views. Different views may provide information of different levels of quality varied over time, and thus should be assigned with different attention scores as well. Unfortunately, the existing attention-based architectures cannot be directly used to jointly learn the attention scores in both time and view domains, due to the data structure complexity. Towards this end, we propose a novel multi-view attention network, namely MuVAN, to learn fine-grained attentional representations from multivariate temporal data. MuVAN is a unified deep learning model that can jointly calculate the two-dimensional attention scores to estimate the quality of information contributed by each view within different timestamps. By constructing a hybrid focus procedure, we are able to bring more diversity to attention, in order to fully utilize the multi-view information. To evaluate the performance of our model, we carry out experiments on three real-world benchmark datasets. Experimental results show that the proposed MuVAN model outperforms the state-of-the-art deep representation approaches in different real-world tasks. Analytical results through a case study demonstrate that MuVAN can discover discriminative and meaningful attention scores across views over time, which improves the feature representation of multivariate temporal data.

Given two topics of interest (A, C) that are otherwise disconnected - for instance two concepts: a disease ("Migraine") and a therapeutic substance ("Magnesium") - this paper attempts to find the conceptual bridges (e.g., serotonin (B)) that connects them in a novel way. This problem of mining implicit linkage is known as hypotheses generation and its potential to accelerate scientific progress is widely recognized. Almost all of the prior studies to tackle this problem ignore the temporal dynamics of concepts. This is limiting because it is known that the semantic meaning of a concept evolves over time. To overcome this issue, in this study, we define this problem as mining time-aware Top-k conceptual bridges, and in doing so provide a systematic approach to formalize the problem. Specifically, the proposed model first extracts relevant entities from the corpus, represents them in time-specific latent spaces, and then further reasons upon it to generate novel and experimentally testable hypotheses. The key challenge in this approach is to learn a mapping function that encodes the temporal characteristics of concepts and aligns the across-time latent spaces. To solve this, we propose an effective algorithm that learns precise mapping sensitive to both global and local semantics of the input query. Both qualitative and quantitative evaluations performed on the largest available biomedical corpus substantiate the importance of leveraging the evolutionary semantics of medical concepts and suggests that the generated hypotheses are novel and worthy of clinical trials.

As news reading on social media becomes more and more popular, fake news becomes a major issue concerning the public and government. The fake news can take advantage of multimedia content to mislead readers and get dissemination, which can cause negative effects or even manipulate the public events. One of the unique challenges for fake news detection on social media is how to identify fake news on newly emerged events. Unfortunately, most of the existing approaches can hardly handle this challenge, since they tend to learn event-specific features that can not be transferred to unseen events. In order to address this issue, we propose an end-to-end framework named Event Adversarial Neural Network (EANN), which can derive event-invariant features and thus benefit the detection of fake news on newly arrived events. It consists of three main components: the multi-modal feature extractor, the fake news detector, and the event discriminator. The multi-modal feature extractor is responsible for extracting the textual and visual features from posts. It cooperates with the fake news detector to learn the discriminable representation for the detection of fake news. The role of event discriminator is to remove the event-specific features and keep shared features among events. Extensive experiments are conducted on multimedia datasets collected from Weibo and Twitter. The experimental results show our proposed EANN model can outperform the state-of-the-art methods, and learn transferable feature representations.

In the big data era, the information about the same object collected from multiple sources is inevitably conflicting. The task of identifying true information (i.e., the truths) among conflicting data is referred to as truth discovery, which incorporates the estimation of source reliability degrees into the aggregation of multi-source data. However, in many real-world applications, large-scale data are distributed across multiple servers. Traditional truth discovery approaches cannot handle this scenario due to the constraints of communication overhead and privacy concern. Another limitation of most existing work is that they ignore the differences among objects, i.e., they treat all the objects equally. This limitation would be exacerbated in distributed environments where significant differences exist among the objects. To tackle the aforementioned issues, in this paper, we propose a novel distributed truth discovery framework (DTD), which can effectively and efficiently aggregate conflicting data stored across distributed servers, with the differences among the objects as well as the importance level of each server being considered. The proposed framework consists of two steps: the local truth computation step conducted by each local server and the central truth estimation step taking place in the central server. Specifically, we introduce the uncertainty values to model the differences among objects, and propose a new uncertainty-based truth discovery method (UbTD) for calculating the true information of objects in each local server. The outputs of the local truth computation step include the estimated local truths and the variances of objects, which are the input information of the central truth estimation step. To infer the final true information in the central server, we propose a new algorithm to aggregate the outputs of all the local servers with the quality of different local servers taken into account. The proposed distributed truth discovery framework can infer object truths without delivering any raw data to the central server, and thus can reduce communication overhead as well as preserve data privacy. Experimental results on three real world datasets show that the proposed DTD framework can efficiently estimate object truths with accuracy guarantee, and the proposed UbTD algorithm significantly outperforms the state-of-the-art batch truth discovery approaches.