=Paper= {{Paper |id=Vol-3740/paper-109 |storemode=property |title=Sexism Identification in Social Networks with Generation-based Language Models |pdfUrl=https://ceur-ws.org/Vol-3740/paper-109.pdf |volume=Vol-3740 |authors=Le Minh Quan,Dang Van Thin |dblpUrl=https://dblp.org/rec/conf/clef/QuanT24 }} ==Sexism Identification in Social Networks with Generation-based Language Models== https://ceur-ws.org/Vol-3740/paper-109.pdf
                         Sexism Identification in Social Networks with
                         Generation-based Language Models
                         Notebook for the EXIST Lab at CLEF 2024

                         Le Minh Quan1,2,* , Dang Van Thin1,2
                         1
                             University of Information Technology-VNUHCM, Quarter 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam
                         2
                             Vietnam National University, Ho Chi Minh City, Vietnam


                                        Abstract
                                        This paper demonstrate our participation in the EXIST (sEXism Identification in Social neTworks) at CLEF 2024.
                                        We participate in 3 task: sexism identification (Task 1), sexism intention (Task 2), and sexism categorization
                                        (Task 3). We proposed an ensemble architecture using Large Language Models (LLMs) to tackle these tasks. Our
                                        approach aimed to emulate the human annotation process and gain more insights into fine-tuning LLMs for
                                        classification tasks. Our best performance model achieved 2nd on task 1, 1st on task 2 and 1st on task 3 with hard
                                        label result. Achieving 0.7826, 0.5677 and 0.6004 on F1 score respectively for each task.

                                        Keywords
                                        Llama 2, Large Language Model, LoRA, Fine-tuning LLM, Prompting Engineering, Social media, CLEF 2024,
                                        EXIST 2024




                         1. Introduction
                         Sexism is prejudice, stereotyping or discrimination base on one’s sex or gender, typically against women
                         and girls. This inequality and discrimination against women remains a pervasive issue in modern
                         society and manifesting in online spaces. Sexism affects women in many facets of their lives, including
                         domestic and parenting roles, career opportunities, body image, and life expectations. Moreover, online
                         sexism can influence social media users, particularly teenagers, to develop sexist attitudes or view them
                         as normal and acceptable. The growth of social media platforms like Twitter and Facebook has led to a
                         significant rise in online sexism. This makes the need for automatic tools to identify online sexism even
                         more critical.
                            Identifying sexism on social media is a challenging problem. Sexist messages can be overtly offensive
                         and hateful, but they can also be subtle, disguised as humor or friendly posts. To address this problem,
                         EXIST (sEXism Identification in Social neTworks) was established. EXIST 2024 at CLEF 2024 is the
                         fourth edition of the EXIST challenge that focus at combating sexism on social media. EXIST aims
                         to capture sexism in a broad sense, from explicit misogyny to other subtle expressions that involve
                         implicit sexist behaviours [1, 2]. EXIST 2024 provides tasks to detect sexism behaviours and discourses,
                         identify the intention of the author behind a sexist social media post and categorize the forms of sexism.
                         These tasks are divided into tweet classification and meme classification, focusing on textual messages
                         and image content (particularly memes) on Twitter. Identifying sexism content can also be conflicting
                         due to differences in perspectives among annotators. To account for this problem, EXIST 2024 adopt
                         the Learning With Disagreement (LeWiDi) [3] paradigm for both the development of the dataset and
                         the evaluation of the systems. In the LeWiDi paradigm, models are trained with conflicting or diverse
                         annotations instead of relying on a single "correct" label per sample. This results in two types of output:
                         hard outputs and soft outputs.


                          CLEF 2024: Conference and Labs of the Evaluation Forum, September 09–12, 2024, Grenoble, France
                         *
                           Corresponding author.
                          $ 20520709@gm.uit.edu.vn (L. M. Quan); thindv@uit.edu.vn (D. V. Thin)
                          € https://nlp.uit.edu.vn/ (D. V. Thin)
                           0000-0001-8340-1405 (D. V. Thin)
                                     © 2024 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).


CEUR
                  ceur-ws.org
Workshop      ISSN 1613-0073
Proceedings
   In this paper, we employ Large Language Models to address the first three tasks of EXIST 2024. Below
is a overview of the proposed tasks:

    • Task 1 is a binary classification task. The objective of this task is to decide whether or not a
      given tweet contains sexist expressions or behaviours.
    • Task 2 is a hierarchical multi-class classification task. For the tweets that have been predicted as
      sexist, the objective of this task is to classify each tweet according to the intention of the person
      who wrote it.
    • Task 3 is a hierarchical multi-label classification task. For the tweets that have been predicted as
      sexist, the objective of this task is to categorize them according to the types of sexism.

  This paper presents our approach for the first three tasks of the EXIST 2024 shared task. In section 4,
we introduce our proposed architecture and the models employed for experiments. Section 5 details
the experimental setup, including the evaluation metrics used and the system setting. In section 6, we
present and discuss the experiment result from both the development and evaluation phases. Finally,
our conclusion based on the result will be in section 7.


2. Related Work
The scientific community has established numerous academic events and shared tasks about Sexism
and Hate Speech overall. HatEval 2019 focused on detection of hate speech against immigrants and
women in Twitter [4]. Homo-Mex 2024 focus on Hate Speech Detection Towards the Mexican Spanish
Speaking LGBT+ Population [5]. EDOS 2023 address the the limitations of Binary detection in sexism
detection, and emphasizing the need to provide clear explanations for why something is sexist [6].
DETESTS-Dis 2024 at IberLEF 2024 follow Learning with Disagreement paradigm to detect and classify
racial stereotypes in Spanish social media [7]. These efforts show that sexism and hate speech detection
still remain an active and challenging area of research.
   Previous EXIST shared task (EXIST 2023) have attracted many research teams to participate. Partici-
pants have achieved good results and provided insightful research. Below are some works that achieved
top results in the EXIST 2023 shared task.

    • Kelkar et al. [8] evaluated multiple different approach, ranging from classic classification
      methods like Multinomial Naive Bayes and Linear Support Vector Classifiers to deep learning
      methods like Multi-Layer Perceptrons, XGBoost, and LSTMs with attention. They also explored
      multiple embedding methods. Their research concluded that training models on both languages
      yielded better results compared to training them on separate languages.
    • Erbani et al. [9] used three separate BERT models to fine-tune task 1, 2, and 3. After fine-tuning,
      the models were "frozen" and then connected together. Fully connected layers are added at the
      beginning of the models. This allows the models to share their "different views" of the data from
      their individual training and thus achieve better performance than using single models.
    • Paula et al. [10] employed a combination of two BERT models: Multilingual BERT (mBERT)
      and Cross-lingual Language Model RoBERTa (XLM-RoBERTa). Each model generated its own
      prediction. The final prediction label was then chosen based on the prediction probability. Their
      experiments demonstrated that this ensemble approach significantly improved model performance.
      This research highlights the potential of utilizing ensemble architectures with even larger base
      models for tackling text classification problems.
    • Tian et al. [11] introduced a novel cascade architecture using two large language models (LLMs)
      based on the GPT architecture: GPT-NeoX and BERTIN-GPT-J-6B. The first model is fine-tuned on
      the competition data, this model handles simpler classifications. The second model is sequentially
      fine-tuned on various “Hate speech” data and then fine-tuned on the competition data, this larger
      model tackles more complex samples. A confidence checker system identifies data points that
      are challenging for the smaller model and send them to the larger model. This architecture
      helps the model save computational costs, increase classification speed while still having higher
      performance than conventional ensemble models.
    • Vallecillo-Rodríguez et al. [12] explored two methods to improve model. The first method is
      tested on transformer models including mDeBERTa and XML-RoBERTa, with data augmentation
      by repeating the tweet six times corresponding to six annotator that labeling each tweet sample.
      The second method studies how to integrate annotator information into the training process.
      The research team applied the multi-modal architecture called "Transformer With Tabular". Text
      feature (tweets) are combined with the encoded annotator’s metadata to create a special tensor.
      This tensor will go through a classification model to output the final prediction. Their findings
      revealed that while annotator information did not significantly impact performance on Task
      1 (likely due to its binary nature), it showed promise for Tasks 2 and 3, which involved more
      complex classifications.

   The approaches shown above span from traditional methods such as support vector machine (SVM),
multi-layer perceptron (MLP) to Deep Learning architecture like Convolutional Neural Networks (CNNs)
and Long Short-Term Memory (LSTM) networks. Transformer-base architecture like BERT and XLM
also widely used. Notably, all these proposed methods rely on text classification. Meanwhile, generative
models are growing significantly in both computer vision (e.g., Diffusion Models) and natural language
processing (e.g., Large Language Models). In this paper, we will not only employ Medium-sized Language
model like XLM-RoBERTa for classification tasks, but also leverage the power of Large Language Model
like mT5 and Llama 2.


3. Dataset overview
The dataset is provided by the EXIST shared task, containing Spanish and English tweets from Twitter.
Dataset structure following Learning with disagreement paradigm (LeWiDi) [3], each Tweet sample is
annotated by six annotators with diverse socio-demographic characteristics. Consequently, instead of a
single gold label, the labels consist of six labels annotated by each annotator. The information of each
annotator is provided, including gender, age, ethnicity, study level and country of origin. Table 1 shows
the statistics for the tweet data, combining both English and Spanish text.

Table 1
Tweets Dataset statistic
                        Information            Training    Development        Test
                        N.o samples               6920         1038           2076
                        Max length                795           586           825
                        Min length                 29            41            38
                        Average length            176           180           176
                        Number of tokens        1168350       177972         347100
                        Number of vocabulary     53472         12045         20642

   Table 2 shows the statistics for the labels of each task, using the official gold labels provided by the
shared task. Task 1 categorizes tweets as sexist or not sexist (yes, no). Task 2 classify the intention of
the author who wrote the sexist tweet (direct, reported, judgemental). Task 3 categorize the types of
a sexist tweet, which can have one or more label (ideological inequality, sexual violent, objectification,
stereotyping dominance, misogyny non-sexual violent). Task 2 and Task 3 follow a two-level hierarchical
structure, as illustrated in Figure 1:
                                                      Tweet




                                         Sexist               Not sexist




       Judgemental   Reported   Direct     Sexual-        Ideological-      Stereotyping-                     Misogyny-non-
                                                                                            Objectification
                                           violence        inequality        dominance                        sexual-violence


Figure 1: Hierarchical Sexism Classification.


Table 2
hard labels statistics
                                                                         Training     Development
                         Task 1
                         NO                                                3367             479
                         YES                                               2697             455
                         Task 2
                         DIRECT                                            1294             204
                         REPORTED                                          459               83
                         JUDGEMENTAL                                       376              75
                         Task 3
                         OBJECTIFICATION                                   1103             183
                         SEXUAL-VIOLENCE                                   675              123
                         STEREOTYPING-DOMINANCE                            1423             241
                         IDEOLOGICAL-INEQUALITY                            1113             212
                         MISOGYNY-NON-SEXUAL-VIOLENCE                      856              158


4. Approach
4.1. Architecture
Base architecture: Our architecture, illustrated in Figure 2, consists of six independent models, referred
to as Component Models. These models share the same model type and training setting. This ensemble
approach emulates the human annotation process, where each model represents a different annotator
with potentially varying biases. Our proposed framework comprises five main components:
   1. Preparing dataset: Each data sample includes metadata of six different annotator. We split the
      dataset by annotator, resulting in six separate dataset. Each dataset contains the same tweets but
      with metadata specific to the corresponding annotator.
   2. Data processing: The sub-samples undergo pre-processing. For LLM models, prompt engineering
      is applied.
   3. Fine-tuning the Component Models: Each Component Model undergoes a separate fine-
      tuning process using its own data picked from one of the six separate datasets. the component
      models have to have the same type, whether it is XLM-RoBERTa or mT5 or Llama 2, and have
      the same system setting.
   4. Post processing: The prediction outputs from the six Component Models are collected and
      post-processed to the required submission format
   5. Final output: The Component Predictions are converted into two type of outputs, soft label and
      hard label:
           • Soft labels: To generate soft labels, we calculate probability distribution for each possible
             classes. In tasks 1 and 2, the sum of these probabilities must be 1.0. For task 3, the sum of
             probability does not necessarily need to be 1.0 because of the multi-label structure.
          • Hard labels: To generate the hard labels from the predicted outputs, we follow the proba-
            bilistic threshold used in the official gold label. For tasks 1 (mono-label), the class annotated
            by more than 3 annotators is selected. For tasks 2 (mono-label), the class annotated by more
            than 2 annotators is selected. Finally, for tasks 3 (multi-label), the class annotated by more
            than 1 annotator are selected. In cases where no class meets the threshold, a random class
            is chosen.
Integrating Hierarchical architecture: Task 2 and Task 3 follow hierarchical structure. To address
these tasks, we modified our architecture such that Component Models for Tasks 2 and 3 only make
predictions for sub-samples classified as sexist. We rely on the Predictions make by Component Models
of Task 1 to get the classified labels (YES, NO). Our base architecture incorporates a hierarchical structure,
as shown in Figure 3


                                                                                 Component Predictions
                                                         POST
                                    OUTPUT
                                                      PROCESSING




                                                         Component Models:
                                                                             Model       Model     Model     Model   Model   Model




      Sample A:                                                                                  DATA PROCESSING


                       1st Annot      2nd Annot      3rd Annot
                      information    information    information

        Tweet     ✳
                       4th Annot      5th Annot      6th Annot
                      information    information    information              Tweet       Tweet     Tweet     Tweet   Tweet   Tweet



Figure 2: Overall Ensemble architecture proposed for EXIST 2024 shared task.


                                                                              POST
                                                   OUTPUT
                                                                           PROCESSING




                                                   Component Predictions

                                                                  NO                             NO




                          Component Models:
                                                   Model                Model        Model                 Model




                                                                       DATA PROCESSING




                                                   Tweet                Tweet        Tweet                 Tweet



                                                   YES            NO       YES        YES        NO        YES


Figure 3: Ensemble architecture with Hierarchical for Task 2 and Task 3 of EXIST 2024 shared task.
4.2. Model Overview
In this paper, we leverage two types of language models: large language models (LLMs) with
Multilingual T5 (mT5) and Llama 2 and a smaller transformer-base language model XLM-RoBERTa.

XLM-RoBERTa [13]: XLM-RoBERTa (XLM-R) is a Multilingual language model base on RoBERTa. It
leverages the Transformer architecture and is trained using a multilingual masked language modeling
objective. XLM-R has been shown to outperform multilingual BERT (mBERT) on various cross-lingual
benchmarks. Our approach using XLM-RoBERTa is described below:

    • Pre-processing: For XLM-RoBERTa, we apply multiple pre-processing methods to the tweet
      dataset as follows.
         1. Link conversion: We use regex to match URLs from tweet and convert them to "URL"
            token.
         2. Mention conversion: We convert user mentions (@username) in tweets to "USER" tokens.
         3. Hashtag conversion: We convert hashtags into separate words (For example, "#DeepLearn-
            ing" will be converted to "Deep Learning").
         4. label conversion: For tasks 1 and 2, labels are converted to numerical representations. For
            multi-label task 3, labels are converted to binary representations.
    • Integrating metadata: To integrate annotator metadata to the input, we add a [SEP] token to
      separate each metadata and the tweet. For example:
         – Original data: Tweet: "Lo sentimos, el meme aún está en construcción."; Annotator’s
           information: gender: female, age: 23-45, ethicities: White or Caucasian, education level:
           Bachelor’s degree, country: Spain.
         – Processed data: "Lo sentimos, el meme aún está en construcción.[SEP]female[SEP]23-
           45[SEP]White or Caucasian[SEP]Bachelor’s degree[SEP]Spain"
    • Fine-tuning: We fine-tune the pre-trained XLM-RoBERTa using the Trainer API from Hugging-
      Face’s library. We fine-tune each task separately with different parameter setting.
    • Post Processing: Post-processing involves converting the output label to the submission format.
      This step transforms the numerical or binary label output by models to original natural language
      format.

Multilingual T5 [14]: Multilingual T5 (mT5) is a LLMs and a multilingual variant of T5. It was
pre-trained on a new Common Crawl dataset containing 101 languages. T5 uses a basic encoder-decoder
Transformer architecture [15] and pre-trained on a masked language modeling “span-corruption”
objective, where the entire spans of tokens are selected for corruption at once. T5 excel at multiple task
such as question answering, summarization, translation. Our approach using mT5 is described below:

    • Pre-processing: Our experiments show that for mT5 in this work, performing better with tweet
      in their original format. This mean keeping elements like user mentions, links, and emojis rather
      than converting them to specific tokens or removing them. We only convert hashtags to separate
      words.
    • Prompting: We format the input by adding a task prefix before the tweet and the section indicator
      before the annotator’s metadata. For the task prefix, we use short phrases such as "Classify"
      or "Multi-label Classify". To indicate a section containing the annotator’s information, we use
      phrases like "Context" or "Information". Here is the example for prompts used for each task:
         1. Prompt: Classify: Lo sentimos, el meme aún está en construcción Information: male, 46+,
            White or Caucasian, Master’s degree Response: YES
         2. Prompt: Multiclass Classify: Lo sentimos, el meme aún está en construcción Context: male,
            46+, White or Caucasian, Master’s degree Response: JUDGEMENTAL
         3. Prompt: Classify sexism types of the following tweet: Lo sentimos, el meme aún está en
            construcción Information of annotator: male, 46+, White or Caucasian, Master’s degree
            Response: OBJECTIFICATION, SEXUAL-VIOLENCE
    • Fine-tuning: We leverage the Hugging Face library’s Trainer API to fine-tune the pre-trained
      mT5 model for each task separately. Each task utilizes different parameter settings to optimize
      performance.


Table 3
Llama 2’s Prompt engineering for Task 1.
               [INST]
               Imagine you are a person with the following characteristics: female, 23-45 years
               old, White or Caucasian ethnicity, Bachelor’s degree, and residing in Spain. Now
               classify the sentiment of a tweet: "Lo sentimos, el meme aún está en construcción"
   Prompt:     ## If the tweet contains any form of sexism or describes situations involving discrimination
               against women, classify it as "YES".
               ## If the tweet does not exhibit prejudice, underestimate, or discriminate against women,
               classify it as "NO". Answer only YES or NO.
               Answer: [/INST]
   Response:   YES


Table 4
Llama 2’s Prompt engineering for Task 2.
               [INST]
               Imagine you are a person with the following characteristics: female, 23-45 years
               old, White or Caucasian ethnicity, Bachelor’s degree, and residing in Spain. Now
               classify the sentiment of a tweet: "Lo sentimos, el meme aún está en construcción"
               ## If the intention of the tweet is to write a message that is sexist by itself, classify as
               "DIRECT"
  Prompt:
               ## If the intention of the tweet is to report or describe a sexist situation or event suffered
               by a woman or women in first or third person, classify as "REPORTED".
               ## If the intention of the tweet is to be judgemental and the tweet describes sexist situations
               or behaviors with the aim of condemning them, classify as "JUDGEMENTAL". Answer only
               DIRECT, REPORTED, or JUDGEMENTAL.
               Answer: [/INST]
  Response:    REPORTED

LLaMA 2 [16]: Llama 2 is a large language model developed by Meta AI and is the successor to their
original Llama model. Llama 2 uses the standard transformer architecture and applies pre-normalization
using RMSNorm. The model employs the SwiGLU activation function, grouped-query attention (GQA),
and rotary positional embeddings. Both the context length and the pre-training corpus size have been
increased compared to the previous model. Unlike other models in this paper, Llama 2 was primarily
trained on English data. Llama 2 surpasses its predecessor in various tasks, including Reasoning, Coding,
and Knowledge. Our approach using Llama 2 is described below:

    • Pre-processing: Like mT5, Llama 2 performs better with tweet in their original format. Therefore,
      we only convert hashtags to separate words.
    • Prompting: Our observation shows that providing more information, such as the label’s descrip-
      tion to the prompt, leads to better model performance. Additionally, having distinct separators
      between each part of the prompt helps to clarify the instructions and makes them easier for the
      model to understand. A special token [INST] is utilized to separate the input prompt and answer
      segments. Prompts used for each task are shown in Table 3, 4, 5.
    • Fine-tuning: We fine-tune the pre-trained Llama 2 with the LoRA method from HuggingFace’s
      library. Each task are fine-tuned separately, with different parameter settings.
  Table 5
  Llama 2’s Prompt engineering for Task 3.
                [INST]
                Imagine you are a person with the following characteristics: female, 23-45 years
                old, White or Caucasian ethnicity, Bachelor’s degree, and residing in Spain. Now
                classify the sentiment of a tweet: "Lo sentimos, el meme aún está en construcción"
                ## If the tweet rejects equality between men and women, classify as "IDEOLOGICAL-
                INEQUALITY".
                ## If the tweet implies that men are superior to women, classify as "STEREOTYPING-
                DOMINANCE"
    Prompt:     ## If the tweet objectifies women, classify it as "OBJECTIFICATION"
                ## If the tweet contains sexual suggestions, or harassment of a sexual nature, classify
                as "SEXUAL-VIOLENCE".
                ## If the tweet expresses hatred and violence towards women without being sexual in
                nature, classify as "MISOGYNY-NON-SEXUAL-VIOLENCE".
                ## Answer only these category IDEOLOGICAL-INEQUALITY, STEREOTYPING-
                DOMINANCE, OBJECTIFICATION, SEXUAL-VIOLENCE, MISOGYNY-NON-
                SEXUAL-VIOLENCE. You can choose more than one category if applicable.
                Answer: [/INST]
    Response:   IDEOLOGICAL-INEQUALITY, STEREOTYPING-DOMINANCE


   • Low-rank Adaptation: To fine-tune Llama 2, we used Parameter-Efficient Fine-Tuning (PEFT)
     method called LoRA. LoRA (Low-Rank Adaptation for Large Language Models) is a popular
     technique to fine-tune Large pre-trained models such as LLMs and diffusion models. LoRA allows
     us to train some dense layers in a neural network indirectly by optimizing rank decomposition
     matrices of the dense layers change during adaptation instead, while keeping the pre-trained
     weights frozen [17]. In short, LoRa reduce the number of trainable parameters, making the
     training process faster and less computational cost, while maintaining strong performance on
     downstream tasks.


5. Experimental Setup
5.1. Evaluation Metric
We evaluate our model’s performance using a combination of metrics for all tasks and all types of
evaluation (soft label and hard label):

   • Hard Label Evaluation:
        – ICM (Information Contrast Measure): ICM is a similarity function that generalizes Point-
          wise Mutual Information (PMI), and can be used to evaluate system outputs in classification
          problems by computing their similarity to the ground truth categories [18].
        – F1-score: F1-score measure of the harmonic mean of precision and recall.
   • Soft Label Evaluation:
        – ICM Soft: A modified ICM metric that accepts both soft system outputs and soft ground
          truth assignments for soft label evaluation.
        – Cross Entropy: Cross Entropy measures the difference between the true label distribution
          and the predicted probability distribution. Cross Entropy only applicable for Tasks 1 and 2.

5.2. System Setting
We use the PyTorch framework and HuggingFace’s Transformers library [19] for our system. We
conducted fine-tuning on various Language models and their variants for each task:
    • Llama 2
         – Model Variants: We use Llama 2 7B Chat model. This is the fastest and lightest model in
           the Llama 2 family and has been fine-tuned specifically for dialogue.
         – Training setting: We used a learning rate of 2e-4 and a batch size of 4. We used the
           Parameter-Efficient Fine-Tuning (PEFT) method LoRA and the AdamW optimizer [20]. We
           only fine-tune task 1 for 1 epoch. Task 2 and task 3 were fine-tuned for 5 epochs.
         – LoRA setting: For Causal Language Modeling, we configured LoRA with an attention
           dimension "r" of 8, an alpha parameter "LoRA_alpha" of 16, and a dropout probability
           "lora_dropout" of 0.05. For target modules, all trainable modules of Llama 2 were included:
           gate_proj, up_proj, down_proj, q_proj, k_proj, v_proj, and o_proj.With LoRA, the required
           training time and resources are significantly reduced. The number of training parameters is
           reduced from approximately 7 billion to approximately 20 million.
         – Processing unit: A100 80G GPU
    • XLM RoBERTa
         – Model Variants: We conduct experiments on two XLM-RoBERTa model sizes: Base and
           Large
         – Training setting: We used a learning rate of 2e-5 and a batch size of 8. For the optimizer,
           we used AdamW. For regularization, we apply Weight Decay (L2 regularization) of 0.01. We
           set Warm-up steps to 100. This allows the model to slowly adjust to the data and mitigate
           the risk of divergence in the initial stages. We fine-tuned the model for 10 epochs for Task
           1, and 20 epochs for Task 2 and Task 3.
         – Processing unit: A100 80G GPU for XLM-R Large, P100 16G GPU for XLM-R Base
    • Multilingual T5
         – Model Variants: We conduct experiment on three mT5 model sizes: Small, Base and Large
         – Training setting: We used a learning rate of 3e-4, a batch size of 16, and the AdamW
           optimizer for fine-tuning. We fine-tuned all three Tasks for 15 epochs.
         – Processing unit: A100 80G GPU for mT5 Large, P100 16G GPU for mT5 Base and mT5
           Small.


6. Result and Discussion
6.1. Development Phase
This section presents the model’s performance on the development dataset. We compare the performance
of different models and variants. Table 6 details our results on hard label, while Table 7 details our results
on soft label. To ensure a fair comparison of Task 2 and Task 3 results, we used the true labels from the
dataset for the first hierarchical level instead of predictions from Task 1. Therefore, these results are
only used to compare model performance and should not be considered the actual performance on data.


Table 6
Hard label results on development set.
                           Task 1                          Task 2                          Task 3
   Model
                ICM     ICM Norm    F1-score    ICM     ICM Norm    F1-score    ICM     ICM Norm    F1-score
 XLM-R base    0.4402     0.7202     0.8134    0.7396     0.7312     0.6650    0.9214     0.7052     0.7042
 XLM-R large   0.5095     0.7549     0.8365    0.8041     0.7514     0.6902    1.0068     0.7242     0.7235
 mT5 small     0.1686     0.5843     0.7222    0.4869     0.6522     0.5313    0.7669     0.6708     0.6679
 mT5 base      0.2038     0.6019     0.7339    0.5403     0.6689     0.5493    0.0893     0.5199     0.5066
 mT5 large     0.4314     0.7158     0.8098    0.6270     0.6960     0.5897    0.9017     0.7008     0.6950
 Llama 2       0.6235     0.8119     0.8746    0.9583     0.7996     0.7471    0.9602     0.7138     0.7116
Table 7
Soft label evaluating results.
                                  Task 1                                     Task 2                              Task 3
   Model
               ICM Soft    ICM Soft Norm   Cross Entropy   ICM Soft   ICM Soft Norm   Cross Entropy   ICM Soft    ICM Soft Norm
 XLM-R base      0.6335        0.6023          1.4940        0.4352       0.5349          1.9023        0.2396         0.5127
 XLM-R large     0.9706        0.6568          1.2474       0.7208       0.5578           1.9068       0.5924          0.5313
 mT5 small      -0.1815        0.4706          1.1619       -0.0628       0.4949          1.8849       -0.5319         0.4718
 mT5 base       -0.0013        0.4997         1.1495         0.2413       0.5193          1.8241       -3.2413         0.3282
 mT5 large       0.5845        0.5944          1.1795        0.4844       0.5388         1.7933         0.0349         0.5018
 Llama 2        0.9980        0.6612           1.5768        0.6728       0.5539          1.9209        0.3020         0.5160



   On hard label evaluation, Llama 2 achieves the best results for both Task 1 (ICM Norm: 0.8119,
F1-score: 0.8746) and Task 2 (ICM Norm: 0.7996, F1-score: 0.7471). This suggests its strong text
understanding capabilities effectively translate to classification tasks. For Task 3, Llama 2 performed on
par with XLM-R large, with scores differing by only about 1% on both ICM Norm and F1-score. mT5
models consistently underperformed across all three tasks. Notably, even mT5 large’s results were
significantly lower than other models. This suggests that mT5 might not be well-suited for these tasks,
possibly due to the complexity of the input sequences, which combine tweet and annotator information.
   Llama 2 achieved the best results on Task 1 for soft labels. However, XLM-R large outperformed all
models on Tasks 2 and 3. Llama-2’s high performance on hard labels but not on soft labels suggests
it might not be learning annotator’s information or, more likely, is ignoring it due to the prompt
construction. XLM-R, on the other hand, is not reliant on prompt engineering and likely processes the
entire input, leading to more diverse soft outputs. Notably, all three models achieved low ICM Soft
Norm scores ranging from 40% to 66%. This indicates that capturing the complexity of the LeWiDi
paradigm distribution might be a challenging problem.

6.2. Evaluation Phase
Task 1: As shown in Table 8, in the Hard-hard evaluation method, Llama 2 achieved the best result
(2th place) with an ICM Norm of 0.7994 and an F1-score of 0.7826 for the positive class. XLM-R large
came in 7th place with an ICM Norm of 0.7898, and mT5 large achieved the lowest with an ICM Norm
of 0.6952. In the Soft-soft evaluation method. XLM-R large achieved the best result, ranking 4th place
with an ICM Soft Norm of 0.6490.

Table 8
Submission results on Task 1
                                    Hard - hard                                              Soft-soft
   Model
                 ICM       ICM Norm F1-score (YES)         Ranking    ICM Soft    ICM Soft Norm Cross Entropy         Ranking
 XLM-R large    0.5766       0.7898         0.7823            7        0.9291        0.6490            1.2637         4
 mT5 large      0.3884       0.6952         0.7292           40         0.4594        0.5737           1.2164         20
 Llama 2        0.5957       0.7994         0.7826            2         0.8316        0.6333           1.6727         7


Task 2: Table 9 showcases our model performance on two evaluation methods. In the Hard-hard
evaluation, our method using Llama 2 achieves 1st rank with ICM Norm at 0.6320 and F1-score at 0.5677.
XLM-R large at 6th rank with ICM Norm at 0.5926, and mT5 large falls short with ICM Norm at 0.4555.
While Llama 2 excelled in the Hard-hard evaluation, its performance faltered in the Soft-soft evaluation.
XLM-R large emerged as the leader, ranking 7th with an ICM Soft Norm at 0.3513.

Table 9
Submission results on Task 2
                                  Hard - hard                                               Soft-soft
    Model
                   ICM      ICM Norm F1-score         Ranking     ICM Soft       ICM Soft Norm Cross Entropy          Ranking
 XLM-R large      0.2847      0.5926      0.5289         6         -1.8462          0.3513            2.4123             7
 mT5 large       -0.1368      0.4555      0.4182        30         -2.0149           0.3377           2.3892            10
 Llama 2         0.4059       0.6320      0.5677         1         -2.9080           0.2657           2.7595            18


Task 3: Our results are presented in Table 10. In the Hard-hard evaluation, XLM-R large comes in
at a close second to 1st place of Llama 2, with ICM Norms of 0.5822 and 0.5862, respectively. XLM-R
maintains its lead in the Soft-soft evaluation, ranking 7th with an ICM Soft Norm of 0.3143.

Table 10
Submission results on Task 3
                                     Hard - hard                                Soft-soft
    Model
                   ICM         ICM Norm F1-score       Ranking   ICM Soft     ICM Soft Norm      Ranking
 XLM-R large      0.3540         0.5822       0.6042      2       -3.5160        0.3143             7
 mT5 large       -0.1090         0.4747       0.5286     12       -3.5438        0.3129             8
 Llama 2         0.3713          0.5862      0.6004       1       -4.5913        0.2576            13



7. Conclusion
This paper describes our approach utilizing the pre-trained Large Language Models (LLMs) for the
classification tasks in the EXIST 2024 Shared task at CLEF 2024. We employed ensemble architectures
to generate both soft and hard predictions for all three tasks. Our experiments highlight the strong
text understanding capabilities of the Large Language Model Llama 2, allowing it to tackle various
classification tasks with high accuracy on hard-hard evaluation method. However, the complexities of
the LeWiDi paradigm distribution, which involves understanding diverse cultural and social perspectives
presented a challenge. In future work, we will delve deeper into prompting techniques, such as Chain-
of-Thought Prompting to encourage LLMs to consider the diversity of human perspectives.


Acknowledgements
This research was supported by The VNUHCM-University of Information Technology’s Scientific
Research Support Fund.


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