Malta

We describe a new weakly supervised method for sentence-level event detection, based exclusively on linear prototype patterns like &quot;people got sick&quot; or &quot;a roadside bomb killed people&quot;. We propose a new BERT based algorithm for approximate pattern matching to identify event phrases, semantically similar to these prototypes. To the best of our knowledge, a similar approach has not been used in the context of event detection. We experimented with two event corpora in the area of disease outbreaks and terrorism and we achieved promising results in sentence level event identification: 0.78 F1 score for new disease cases detection and 0.68 F1 in detecting terrorist attacks. Results were in line with some state-of-the-art systems.

EACL 2024

Leveraging Approximate Pattern Matching with BERT for Event Detection

approximate pattern matching

bert. prototypes

pattern matching

event detection

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ACL 2024

The 62nd Annual Meeting of the Association for Computational Linguistics (ACL 2024) will take place in Bangkok, Thailand from August 11th to 16th, 2024. More information will be announced soon.

We describe a new weakly supervised method for sentence-level event detection, based exclusively on linear prototype patterns like "people got sick" or "a roadside bomb killed people". We propose a new BERT based algorithm for approximate pattern matching to identify event phrases, semantically similar to these prototypes. To the best of our knowledge, a similar approach has not been used in the context of event detection. We experimented with two event corpora in the area of disease outbreaks and terrorism and we achieved promising results in sentence level event identification: 0.78 F1 score for new disease cases detection and 0.68 F1 in detecting terrorist attacks. Results were in line with some state-of-the-art systems.

workshop paper

Welcome to the 18th Conference of the European Chapter of the Association for Computational Linguistics (EACL). Continuing its mission of expanding and involving the science community of all European countries, EACL has selected the Malta community for the 18th EACL. Considering the importance of physical interaction among researchers, the conference will be held at the Hotel Radisson Blu, St. Julians, in Malta, from 17 to 22 of March, 2024. The conference will also feature the possibility to participate virtually. As the flagship European conference in the field of computational linguistics, EACL welcomes European and international researchers covering a broad spectrum of research areas that are concerned with computational approaches to natural language. 
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To access the EACL 2024 event page you need to register [**here**](https://acl.swoogo.com/EACL2024). 

As the flagship European conference in the field of computational linguistics, EACL welcomes European and international researchers covering a broad spectrum of research areas that are concerned with computational approaches to natural language.

There is a large and growing body of literature on datasets created to facilitate the study of socio-political events of conflict and unrest. However, the datasets, and the approaches taken to create them, vary a lot depending on the type of research they are intended to support. For example, while scholars from natural language processing (NLP) tend to focus on annotating specific spans of text indicating various components of an event, scholars from the disciplines of political science and conflict studies tend to focus on creating databases that code an abstract but structured representation of the event, less tied to a specific source text. The survey presented in this paper aims to map out the current landscape of available event datasets within the domain of social and political conflict and unrest ‚Äì both from the NLP and political science communities ‚Äì offering a unified view of the work done across different disciplines.

Socio-political Events of Conflict and Unrest: A Survey of Available Datasets

ChatGPT, developed by OpenAI, has made a significant impact on the world, mainly on how people interact with technology. In this study, we evaluate ChatGPT's ability to detect hate speech in Turkish tweets and measure its strength using zero- and few-shot paradigms and compare the results to the supervised fine-tuning BERT model. On evaluations with the SIU2023-NST dataset, ChatGPT achieved 65.81 accuracy in detecting hate speech for the few-shot setting, while BERT with supervised fine-tuning achieved 82.22 accuracy. This results supports previous findings that show that, despite its much smaller size, BERT is more suitable for natural language classifications tasks such as hate speech detection.

Evaluating ChatGPT's Ability to Detect Hate Speech in Turkish Tweets

This paper introduces a zero-shot hate detection experiment using a multimodal large model. Although the implemented model comprises an unsupervised method, results demonstrate that its performance is comparable to previous supervised methods. Furthemore, this study proposed experiments with various prompts and demonstrated that simpler prompts, as opposed to the commonly used detailed prompts in large language models, led to better performance for multimodal hate speech event detection tasks. While supervised methods offer high performance, they require significant computational resources for training, and the approach proposed here can mitigate this issue. The code is publicly available at https://github.com/yamagishi0824/zeroshot-hate-detect.

YYama@Multimodal Hate Speech Event Detection 2024: Simpler Prompts, Better Results - Enhancing Zero-shot Detection with a Large Multimodal Model

This paper describes the system that participated in the Climate Activism Stance and Hate Event Detection shared task organized at The 7th Workshop on Challenges and Applications of Automated Extraction of Socio-political Events from Text (CASE 2024). The system tackles the important task of hate speech detection by combining large language model predictions with manually designed features, while trying to explain where the LLM approach fails to predict the correct results.

RACAI at ClimateActivism 2024: Improving Detection of Hate Speech by Extending LLM Predictions with Handcrafted Features

In the context of the proliferation of multimodal hate speech related to the Russia-Ukraine conflict, we introduce a unified multimodal fusion system for detecting hate speech and its targets in text-embedded images. Our approach leverages the Twitter-based RoBERTa and Swin Transformer V2 models to encode textual and visual modalities, and employs the Multilayer Perceptron (MLP) fusion mechanism for classification. Our system achieved macro F1 scores of 87.27 for hate speech detection and 80.05 for hate speech target detection in the Multimodal Hate Speech Event Detection Challenge 2024, securing the 1st rank in both subtasks. We open-source the trained models at https://huggingface.co/Yestin-Wang

CLTL@Multimodal Hate Speech Event Detection 2024: The Winning Approach to Detecting Multimodal Hate Speech and Its Targets

CASE in EACL 2024 proposes the shared task on Hate Speech and Stance Detection during Climate Activism. In our participation in the stance detection task, we have tested different approaches using LLMs for this classification task. We have tested a generative model using the classical seq2seq structure. Subsequently, we have considerably improved the results by replacing the last layer of these LLMs with a classifier layer. We have also studied how the performance is affected by the amount of data used in training. For this purpose, a partition of the dataset has been used and external data from posture detection tasks has been added.

HAMiSoN-Generative at ClimateActivism 2024: Stance Detection using generative large language models

The automatic identification of hate speech constitutes an important task, playing a relevant role towards inclusivity. In these terms, the shared task on Climate Activism Stance and Hate Event Detection at CASE 2024 proposes the analysis of Twitter messages related to climate change activism for three subtasks. Subtasks A and C aim at detecting hate speech and establishing the stance of the tweet, respectively, while subtask B seeks to determine the target of the hate speech. In this paper, we describe our approach to the given subtasks. Our systems leverage transformer-based multi-task learning. Additionally, since the dataset contains a low number of tweets, we have studied the effect of adding external data to increase the learning of the model. With our approach we achieve the fourth position on subtask C on the final leaderboard, with minimal difference from the first position, showcasing the strength of multi-task learning.

HAMiSoN-MTL at ClimateActivism 2024: Detection of Hate Speech, Targets, and Stance using Multi-task Learning

The paper presents the approach developed for the "Climate Activism Stance and Hate Event Detection" Shared Task at CASE 2024, comprising three sub-tasks. The Shared Task aimed to create a system capable of detecting hate speech, identifying the targets of hate speech, and determining the stance regarding climate change activism events in English tweets. The approach involved data cleaning and pre-processing, addressing data imbalance, and fine-tuning the "mistralai/Mistral-7B-v0.1" LLM for sequence classification using PEFT (Parameter-Efficient Fine-Tuning). The LLM was fine-tuned using two PEFT methods, namely LoRA and prompt tuning, for each sub-task, resulting in the development of six Mistral-7B fine-tuned models in total. Although both methods surpassed the baseline model scores of the task organizers, the prompt tuning method yielded the highest results. Specifically, the prompt tuning method achieved a Macro-F1 score of 0.8649, 0.6106 and 0.6930 in the test data of sub-tasks A, B and C, respectively.

NLPDame at ClimateActivism 2024: Mistral Sequence Classification with PEFT for Hate Speech, Targets and Stance Event Detection

Climate activism has emerged as a powerful force in addressing the urgent challenges posed by climate change. Individuals and organizations passionate about environmental issues use platforms like Twitter to mobilize support, share information, and advocate for policy changes. Unfortunately, amidst the passionate discussions, there has been an unfortunate rise in the prevalence of hate speech on the platform. Some users resort to personal attacks and divisive language, undermining the constructive efforts of climate activists. In this paper, we describe our approaches for three subtasks of ClimateActivism at CASE 2024. For all the three subtasks, we utilize pretrained language models enhanced by ensemble learning. Regarding the second subtask, dedicated to target detection, we experimented with incorporating Named Entity Recognition in the pipeline. Additionally, our models secure the second, third and fifth ranks in the three subtasks respectively.

AAST-NLP at ClimateActivism 2024: Ensemble-Based Climate Activism Stance and Hate Speech Detection : Leveraging Pretrained Language Models

Social media users often express hate speech towards specific targets and may either support or refuse activist movements. The automated detection of hate speech, which involves identifying both targets and stances, plays a critical role in event identification to mitigate its negative effects. In this paper, we present our methods for three subtasks of the Climate Activism Stance and Hate Event Detection Shared Task at CASE 2024. For each subtask (i) hate speech identification (ii) targets of hate speech identification (iii) stance detection, we experiment with optimized Transformer-based architectures that focus on tweet-specific features such as hashtags, URLs, and emojis. Furthermore, we investigate generative large language models, such as Llama2, using specific prompts for the first two subtasks. Our experiments demonstrate better performance of our models compared to baseline models in each subtask. Our solutions also achieve third, fourth, and first places respectively in the subtasks.

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