Comment optimiser les formats d’entrée et de sortie pour la génération de texte BERT ?

Putting BERT to use in the real world often requires a deeper understanding of the architecture behind it and the data that it was trained on. While BERT can capture complex textual relationships, it is critical to ensure that the training data is representative of the target task. It is not only about fine-tuning BERT for a specific task, but also about understanding the nuances of the data and the business problem at hand.

BERT (Bidirectional Encoder Representations from Transformers) is a language model that learns contextual word representations by looking at both left and right contexts. It uses transformer architecture and is pre-trained on large text corpora. 1. Input format: Use special tokens [CLS] at the start and [SEP] to separate sentences. Tokenize text using WordPiece. 2. Fine-tune BERT for your specific task by adding task-specific layers on top. 3. Output format: For generation, use the final hidden states as input to a decoder. Apply decoding strategies. 4. Evaluate quality and diversity using metrics like BLEU, ROUGE, and Self-BLEU. 5. Experiment with different hyperparameters, input representations, and decoding methods

Imagine you're reading a book but, unlike the usual way of reading from start to finish, you're able to understand each word based on its context, considering not just the words before it but also those after it. That's how BERT works. It reads and comprehends language in a way that considers the full context of a word by looking at the words that come before and after it. Traditional language-processing systems typically read text in order, either from left to right or right to left. BERT, however, breaks this norm by reading the entire sentence or paragraph all at once. This is like having an all-around view of a street scene rather than just a one-way view. This is how models like BERT can capture the complexity and nuance in language.

BERT is like a super-smart reader: 📚 It can understand words from both the beginning and end of a sentence. This makes it better at understanding the meaning of the whole sentence. You can teach BERT new things: 🎓 You can give it more information about a specific task. For example, you can teach it to answer questions or write different kinds of text.

We could scan the documents or long text by chunking the text by maximum length. That is by striding over the entire document. So for example for a pdf of 20 pages dividing by maximum length would create around 30 to 40 chunks of text. This is one approach which I would like to mention. Another best way is to work by sentence. Work by sentence ? Let me explain how working by extracting the sentence would be a meaningful approach as the model could understand the semantic representations better than the previous case of dividing by maximum length. Here the model could represent the tokens in the latent space better for a sentence based transformer than an uncased Bert.

In our experience deploying LLM locally, we found that domain-specific tokenization and keyword segmentation are essential. By incorporating task-specific keywords into the input sequence, BERT captures the nuances and produces more relevant outputs. This aligns with our method of fine-tuning Llama-3 to provide highly customized responses in sentiment analysis.

Before BERT can work its magic, you must prepare the input correctly. Start with tokenization—breaking down text into bite-sized pieces that BERT can understand. Add special tokens like [CLS] to signal the start and [SEP] to separate different sentences or sections. Also, consider the length of your input. BERT handles up to 512 tokens, so keep it concise and to the point. The better your input, the clearer BERT will understand the task.

Preparing the input for BERT entails not only adding special tokens but also ensuring that the sequence length does not exceed BERT's maximum limit of 512 tokens for the base model. If the text is too long, it must be truncated, split, or otherwise processed, which may interfere with the model's understanding of the content. Furthermore, where the [MASK] tokens are placed is critical. For example, random masking can help the model generalize better than fixed-position masking.

Preparing input for BERT text generation involves structuring the input data in a specific format to leverage the model's capabilities effectively. By incorporating special tokens like [CLS], [SEP], and [MASK], the input sequence is tailored to suit BERT's requirements for generating text. These tokens serve distinct purposes: [CLS] marks the start of the input sequence, [SEP] indicates its end and separates it from the output sequence, while [MASK] designates positions where BERT will generate new tokens. This meticulous preparation ensures that BERT can generate coherent and contextually relevant text outputs based on the provided input sequence, making it a powerful tool for various text generation tasks.

I like to think of the output generation process as a combination of art and science. While the decoding strategies are the norm, it is also important to consider the application's context. Top-k sampling, for example, may be preferred in situations where creativity is desired, such as storytelling or content creation. Beam search, on the other hand, may be more appropriate for more structured outputs such as summaries or translations.

When it comes to generating output from BERT, the process involves feeding the input into the fine-tuned model and obtaining probabilities for each token at masked positions. This sequence of tokens represents the generated text, and various decoding strategies can be employed to select the most probable tokens for filling in the blanks. Decoding methods like greedy decoding, beam search, and top-k sampling each offer unique approaches to generating text from BERT. While greedy decoding prioritizes high-probability tokens at each step, potentially leading to repetitive text, beam search maintains multiple candidate sequences for more diverse outputs.

BERT embeddings can be fine-tuned for specific text generation tasks like text completion, text summarization, or machine translation. In this case, you would train an additional neural network on top of BERT's embeddings to generate text sequences.

Generating output from BERT involves a sophisticated process that leverages the model's capabilities to produce coherent and contextually relevant text. By feeding the input to a fine-tuned BERT model, probabilities of each token at masked positions are obtained, enabling the selection of appropriate tokens to fill in the blanks. Various decoding strategies, such as greedy decoding, beam search, and top-k sampling, offer different approaches to generating text outputs. Greedy decoding prioritizes tokens with the highest probabilities at each position, potentially resulting in repetitive text. In contrast, beam search maintains multiple candidate sequences to promote diversity in outputs but may sacrifice coherence.

To generate output from BERT effectively, you'll need to start by supplying your input text to a BERT model that has been fine-tuned for your specific task. The model then calculates probabilities for each token at every masked position.

Evaluating the quality and diversity of text generated by BERT is crucial to assess its effectiveness in various natural language processing tasks. Quality evaluation focuses on how accurately the generated text reflects the input and task requirements, while diversity evaluation considers the novelty and variability of the generated content. To gauge these aspects, utilizing metrics like BLEU, ROUGE, Self-BLEU, and Dist-n can provide valuable insights.

I've discovered that evaluating generated text is frequently more subjective than objective. While metrics such as BLEU and ROUGE provide quantitative measures, human evaluation is still the gold standard for determining the quality, fluency, and relevance of generated content. To get an accurate depiction of the model's performance, it is critical to balance automated metrics with human judgment.

To evaluate these aspects, metrics such as BLEU, ROUGE, Self-BLEU, and Dist-n can be used. BLEU compares the generated text with one or more reference texts, calculating the percentage of matching n-grams. ROUGE does the same but takes into account the order and length of the n-grams.

Evaluating the quality and diversity of BERT-generated text involves using both quantitative and qualitative metrics. Quality is assessed using metrics like BLEU and ROUGE, which compare the generated text to reference texts by measuring n-gram overlaps. Diversity is evaluated using metrics like Self-BLEU, which checks the similarity among generated texts, and Dist-n, which counts the number of distinct n-grams. Higher scores in these metrics indicate better quality and diversity, ensuring that the text is not only accurate but also varied and original.

Studies evaluating machine-generated text data started from Machine Translation (MT) research. The IBM-developed BLUE (Bilingual Evaluation Understudy) was the first. In the context of LLM, MT metrics such as BLUE and ROUGU are widely adopted. While these metrics are focused on quality, diversity is equally important. Self-blue (where lower values show more diversity) and entropy are famous metrics to measure diversity. While using entropy as the metric to evaluate diversity, the lower value shows lower diversity. Monte-Carlo simulation is used in estimating the entropy value of the generated text. Other metrics such as NLL-oracle, MS-Jaccard, and Frechet-BERT Distance are also used.

- 🧠 Carefully designing the input prompts with relevant keywords or phrases that are highly descriptive of the desired output, to guide the BERT model in generating contextually appropriate text. - 🤖 Adjusting the number and placement of mask tokens in the input sequence can significantly influence the nature and relevance of BERT’s outputs. -📊 Experimenting with different decoding strategies like greedy decoding, beam search, or top-k sampling to balance between diversity and accuracy of the generated text. - Utilizing temperature control in sampling decisions 🌡️ can help in fine-tuning the randomness versus determinism of the text output, allowing you to cater to specific creative or formal needs.

Optimizing input and output formats for BERT text generation enhances text quality and diversity. - Design input prompts with relevant keywords or phrases to guide BERT in generating contextually appropriate text. - Adjust mask tokens to influence output relevance and structure. - Experiment with decoding strategies like beam search or top-k sampling for balance between diversity and accuracy. - Use temperature control to fine-tune randomness versus determinism. These strategies ensure coherent, diverse, and efficient text generation with BERT.

Optimizing the input and output formats for BERT text generation plays a crucial role in enhancing the overall performance and effectiveness of the model in generating coherent and diverse text outputs. By carefully structuring the input with relevant and informative content, such as key phrases or summaries, users can guide BERT to produce text that aligns closely with the desired output. Ensuring that the length and number of masks in the input match the expected token length in the output is essential for maintaining consistency and accuracy during text generation. Moreover, leveraging different mask tokens to signify distinct parts of the output can further refine the generated text and improve its overall quality.

Optimizing the input and output formats for BERT text generation is a critical step in enhancing the effectiveness and efficiency of the text generation process. By carefully structuring the input with informative and relevant content, such as key phrases or summaries, users can provide BERT with the necessary context to generate accurate and coherent text outputs. Ensuring that the length and number of mask tokens align with the expected output length is crucial for generating meaningful and complete text. Additionally, utilizing different mask tokens to represent distinct parts of the output can further refine the generation process, enabling BERT to capture nuances and details effectively.

Informative Input: Use keywords, phrases, or sentences that describe the desired output to guide BERT text generation. Masking Strategy: Match the length and number of masks to the expected length and number of tokens in the output eg, use 5 masks for generating five-word sentences. Mask Token Types: Use different mask tokens to indicate different parts of the output eg, use <S> for the start token and </S> for the end token. Experiment with different decoding strategies like beam search, top-k sampling, or temperature, to balance diversity and quality. Tune decoding parameters like beam size, top-k value, or temperature, to achieve optimal results eg, adjusting the temperature can control the randomness of generated text.