Hong Zhang


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Open-Topic False Information Detection on Social Networks with Contrastive Adversarial Learning
Guanghui Ma | Chunming Hu | Ling Ge | Hong Zhang
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing

Current works about false information detection based on conversation graphs on social networks focus primarily on two research streams from the standpoint of topic distribution: in-topic and cross-topic techniques, which assume that the data topic distribution is identical or cross, respectively. This signifies that all test data topics are seen or unseen by the model.However, these assumptions are too harsh for actual social networks that contain both seen and unseen topics simultaneously, hence restricting their practical application.In light of this, this paper develops a novel open-topic scenario that is better suited to actual social networks. In this open-topic scenario, we empirically find that the existing models suffer from impairment in the detection performance for seen or unseen topic data, resulting in poor overall model performance. To address this issue, we propose a novel Contrastive Adversarial Learning Network, CALN, that employs an unsupervised topic clustering method to capture topic-specific features to enhance the model’s performance for seen topics and an unsupervised adversarial learning method to align data representation distributions to enhance the model’s generalisation to unseen topics.Experiments on two benchmark datasets and a variety of graph neural networks demonstrate the effectiveness of our approach.

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E-VarM: Enhanced Variational Word Masks to Improve the Interpretability of Text Classification Models
Ling Ge | ChunMing Hu | Guanghui Ma | Junshuang Wu | Junfan Chen | JiHong Liu | Hong Zhang | Wenyi Qin | Richong Zhang
Proceedings of the 29th International Conference on Computational Linguistics

Enhancing the interpretability of text classification models can help increase the reliability of these models in real-world applications. Currently, most researchers focus on extracting task-specific words from inputs to improve the interpretability of the model. The competitive approaches exploit the Variational Information Bottleneck (VIB) to improve the performance of word masking at the word embedding layer to obtain task-specific words. However, these approaches ignore the multi-level semantics of the text, which can impair the interpretability of the model, and do not consider the risk of representation overlap caused by the VIB, which can impair the classification performance. In this paper, we propose an enhanced variational word masks approach, named E-VarM, to solve these two issues effectively. The E-VarM combines multi-level semantics from all hidden layers of the model to mask out task-irrelevant words and uses contrastive learning to readjust the distances between representations. Empirical studies on ten benchmark text classification datasets demonstrate that our approach outperforms the SOTA methods in simultaneously improving the interpretability and accuracy of the model.


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Discriminating between standard Romanian and Moldavian tweets using filtered character ngrams
Andrea Ceolin | Hong Zhang
Proceedings of the 7th Workshop on NLP for Similar Languages, Varieties and Dialects

We applied word unigram models, character ngram models, and CNNs to the task of distinguishing tweets of two related dialects of Romanian (standard Romanian and Moldavian) for the VarDial 2020 RDI shared task (Gaman et al. 2020). The main challenge of the task was to perform cross-genre text classification: specifically, the models must be trained using text from news articles, and be used to predict tweets. Our best model was a Naive Bayes model trained on character ngrams, with the most common ngrams filtered out. We also applied SVMs and CNNs, but while they yielded the best performance on an evaluation dataset of news article, their accuracy significantly dropped when they were used to predict tweets. Our best model reached an F1 score of 0.715 on the evaluation dataset of tweets, and 0.667 on the held-out test dataset. The model ended up in the third place in the shared task.