Text Embedding-based Event Detection for Social and News Media

Today, social and news media are the leading platforms that distribute newsworthy content, and most internet users access them regularly to get information. However, due to the data’s unstructured nature and vast volume, manual analyses to extract information require enormous effort. Thus, automated intelligent mechanisms have become crucial. The literature presents several emerging approaches for social and news media event detection, along with distinct evolutions, mainly due to the variations in the media. However, most available social media event detection approaches primarily rely on data statistics, ignoring linguistics, making them vulnerable to information loss. Also, the available news media event detection approaches mostly fail to capture long-range text dependencies and support predictions of low-resource languages (i.e. languages with relatively fewer data). The possibility of utilising interconnections between different data levels to improve final predictions also has not been adequately explored. This research investigates how the characteristics of text embeddings built using prediction-based models that have proven capabilities to capture linguistics can be used in event detection while defeating available limitations. Initially, it redefines the problem of event detection based on two data granularities, coarse- and fine-grained levels, to allow systems to tackle different information requirements. Mainly, the coarse-grained level targets the notification of event occurrences and the fine-grained level targets the provision of event details. Following the new definition, this research proposes two novel approaches for coarse- and fine-grained level event detections on social media, Embed2Detect and WhatsUp, mainly utilising linguistics captured by self-learned word embeddings and their hierarchical relationships in dendrograms. For news media event detection, this proposes a TRansformer-based Event Document classification architecture (TRED) involving long-sequence and cross-lingual transformer encoders and a novel learning strategy, Two-phase Transfer Learning (TTL), supporting the capturing of long-range dependencies and data level interconnections. All the proposed approaches have been evaluated on recent real datasets, covering four aspects crucial for event detection: accuracy, efficiency, expandability and scalability. Social media data from two diverse domains and news media data from four high- and low-resource languages are mainly involved. The obtained results reveal that the proposed approaches outperform the state-of-the-art methods despite the data diversities, proving their accuracy and expandability. Additionally, the evaluations on efficiency and scalability adequately confirm the methods’ appropriateness for (near) real-time processing and ability to handle large data volumes. In summary, the achievement of all crucial requirements evidences the potential and utility of proposed approaches for event detection in social and news media

Emoji Powered Capsule Network to Detect Type and Target of Offensive Posts in Social Media

This paper describes a novel research approach to detect type and target of offensive posts in social media using a capsule network. The input to the network was character embeddings combined with emoji embeddings. The approach was evaluated on all three subtasks in Task 6 - SemEval 2019: OffensEval: Identifying and Categorizing Offensive Language in Social Media. The evaluation also showed that even though the capsule networks have not been used commonly in natural language processing tasks, they can outperform existing state of the art solutions for offensive language detection in social media

Transformers to Fight the COVID-19 Infodemic

The massive spread of false information on social media has become a global risk especially in a global pandemic situation like COVID-19. False information detection has thus become a surging research topic in recent months. NLP4IF-2021 shared task on fighting the COVID-19 infodemic has been organised to strengthen the research in false information detection where the participants are asked to predict seven different binary labels regarding false information in a tweet. The shared task has been organised in three languages; Arabic, Bulgarian and English. In this paper, we present our approach to tackle the task objective using transformers. Overall, our approach achieves a 0.707 mean F1 score in Arabic, 0.578 mean F1 score in Bulgarian and 0.864 mean F1 score in English ranking 4th place in all the languages

TTL: transformer-based two-phase transfer learning for cross-lingual news event detection

Today, we have access to a vast data amount, especially on the internet. Online news agencies play a vital role in this data generation, but most of their data is unstructured, requiring an enormous effort to extract important information. Thus, automated intelligent event detection mechanisms are invaluable to the community. In this research, we focus on identifying event details at the sentence and token levels from news articles, considering their fine granularity. Previous research has proposed various approaches ranging from traditional machine learning to deep learning, targeting event detection at these levels. Among these approaches, transformer-based approaches performed best, utilising transformers’ transferability and context awareness, and achieved state-of-the-art results. However, they considered sentence and token level tasks as separate tasks even though their interconnections can be utilised for mutual task improvements. To fill this gap, we propose a novel learning strategy named Two-phase Transfer Learning (TTL) based on transformers, which allows the model to utilise the knowledge from a task at a particular data granularity for another task at different data granularity, and evaluate its performance in sentence and token level event detection. Also, we empirically evaluate how the event detection performance can be improved for different languages (high- and low-resource), involving monolingual and multilingual pre-trained transformers and language-based learning strategies along with the proposed learning strategy. Our findings mainly indicate the effectiveness of multilingual models in low-resource language event detection. Also, TTL can further improve model performance, depending on the involved tasks’ learning order and their relatedness concerning final predictions

WhatsUp: An event resolution approach for co-occurring events in social media

The rapid growth of social media networks has resulted in the generation of a vast data amount, making it impractical to conduct manual analyses to extract newsworthy events. Thus, automated event detection mechanisms are invaluable to the community. However, a clear majority of the available approaches rely only on data statistics without considering linguistics. A few approaches involved linguistics, only to extract textual event details without the corresponding temporal details. Since linguistics define words’ structure and meaning, a severe information loss can happen without considering them. Targeting this limitation, we propose a novel method named WhatsUp to detect temporal and fine-grained textual event details, using linguistics captured by self-learned word embeddings and their hierarchical relationships and statistics captured by frequency-based measures. We evaluate our approach on recent social media data from two diverse domains and compare the performance with several state-of-the-art methods. Evaluations cover temporal and textual event aspects, and results show that WhatsUp notably outperforms state-of-the-art methods. We also analyse the efficiency, revealing that WhatsUp is sufficiently fast for (near) real-time detection. Further, the usage of unsupervised learning techniques, including self-learned embedding, makes our approach expandable to any language, platform and domain and provides capabilities to understand data-specific linguistics

Embed2Detect: temporally clustered embedded words for event detection in social media

Social media is becoming a primary medium to discuss what is happening around the world. Therefore, the data generated by social media platforms contain rich information which describes the ongoing events. Further, the timeliness associated with these data is capable of facilitating immediate insights. However, considering the dynamic nature and high volume of data production in social media data streams, it is impractical to filter the events manually and therefore, automated event detection mechanisms are invaluable to the community. Apart from a few notable exceptions, most previous research on automated event detection have focused only on statistical and syntactical features in data and lacked the involvement of underlying semantics which are important for effective information retrieval from text since they represent the connections between words and their meanings. In this paper, we propose a novel method termed Embed2Detect for event detection in social media by combining the characteristics in word embeddings and hierarchical agglomerative clustering. The adoption of word embeddings gives Embed2Detect the capability to incorporate powerful semantical features into event detection and overcome a major limitation inherent in previous approaches. We experimented our method on two recent real social media data sets which represent the sports and political domain and also compared the results to several state-of-the-art methods. The obtained results show that Embed2Detect is capable of effective and efficient event detection and it outperforms the recent event detection methods. For the sports data set, Embed2Detect achieved 27% higher F-measure than the best-performed baseline and for the political data set, it was an increase of 29%

Event Causality Identification with Causal News Corpus -- Shared Task 3, CASE 2022

The Event Causality Identification Shared Task of CASE 2022 involved two subtasks working on the Causal News Corpus. Subtask 1 required participants to predict if a sentence contains a causal relation or not. This is a supervised binary classification task. Subtask 2 required participants to identify the Cause, Effect and Signal spans per causal sentence. This could be seen as a supervised sequence labeling task. For both subtasks, participants uploaded their predictions for a held-out test set, and ranking was done based on binary F1 and macro F1 scores for Subtask 1 and 2, respectively. This paper summarizes the work of the 17 teams that submitted their results to our competition and 12 system description papers that were received. The best F1 scores achieved for Subtask 1 and 2 were 86.19% and 54.15%, respectively. All the top-performing approaches involved pre-trained language models fine-tuned to the targeted task. We further discuss these approaches and analyze errors across participants' systems in this paper.Comment: Accepted to the 5th Workshop on Challenges and Applications of Automated Extraction of Socio-political Events from Text (CASE 2022

TED-S: Twitter Event Data in Sports and Politics with Aggregated Sentiments

Even though social media contain rich information on events and public opinions, it is impractical to manually filter this information due to data’s vast generation and dynamicity. Thus, automated extraction mechanisms are invaluable to the community. We need real data with ground truth labels to build/evaluate such systems. Still, to the best of our knowledge, no available social media dataset covers continuous periods with event and sentiment labels together except for events or sentiments. Datasets without time gaps are huge due to high data generation and require extensive effort for manual labelling. Different approaches, ranging from unsupervised to supervised, have been proposed by previous research targeting such datasets. However, their generic nature mainly fails to capture event-specific sentiment expressions, making them inappropriate for labelling event sentiments. Filling this gap, we propose a novel data annotation approach in this paper involving several neural networks. Our approach outperforms the commonly used sentiment annotation models such as VADER and TextBlob. Also, it generates probability values for all sentiment categories besides providing a single category per tweet, supporting aggregated sentiment analyses. Using this approach, we annotate and release a dataset named TED-S, covering two diverse domains, sports and politics. TED-S has complete subsets of Twitter data streams with both sub-event and sentiment labels, providing the ability to support event sentiment-based research