NLP

NLP Chapter 7 – Introduction to Transformers and BERT | Modern NLP Models

Introduction to Transformers and BERT in Natural Language Processing

Traditional NLP models such as RNNs and LSTMs struggle with long-range dependencies
and parallel processing. Transformers revolutionized NLP by enabling models to
process entire sequences simultaneously using attention mechanisms.

BERT (Bidirectional Encoder Representations from Transformers) is one of the most
influential transformer-based models and serves as the foundation for many modern
NLP applications, including search engines and conversational AI.

⭐ What are Transformers?

Transformers are deep learning architectures based on self-attention mechanisms.
Unlike RNNs, transformers do not process data sequentially, allowing faster
training and better handling of long texts.

📌 Problems with Traditional RNN-Based Models

  • Difficulty capturing long-term dependencies
  • Slow training due to sequential processing
  • Vanishing and exploding gradient problems

📌 Self-Attention Mechanism

Self-attention allows the model to focus on different parts of a sentence
when processing each word. This enables the model to understand context
more effectively.

Benefits of Self-Attention:

  • Captures global context
  • Handles long sentences efficiently
  • Supports parallel computation

📌 Transformer Architecture

  • Input embeddings + positional encoding
  • Multi-head self-attention
  • Feed-forward neural networks
  • Encoder and decoder blocks

📌 What is BERT?

BERT is a transformer-based model trained using a bidirectional approach.
It understands context from both left and right sides of a word, making
it highly effective for language understanding tasks.

📌 How BERT is Trained

  • Masked Language Modeling (MLM): Predicts masked words in a sentence
  • Next Sentence Prediction (NSP): Learns sentence relationships

📌 BERT Fine-Tuning Example


from transformers import BertTokenizer, BertForSequenceClassification
from transformers import Trainer, TrainingArguments

tokenizer = BertTokenizer.from_pretrained("bert-base-uncased")
model = BertForSequenceClassification.from_pretrained(
    "bert-base-uncased",
    num_labels=2
)

📌 Applications of Transformers and BERT

  • Question answering systems
  • Search engine ranking
  • Text summarization
  • Chatbots and virtual assistants

📌 Project Title

BERT-Based Question Answering and Text Classification System

📌 Project Description

In this project, you will fine-tune a pretrained BERT model to perform tasks
such as question answering or text classification. This project demonstrates
how modern NLP systems achieve state-of-the-art performance.

📌 Summary

Transformers and BERT represent a major leap forward in NLP. By leveraging
self-attention and bidirectional context, these models outperform traditional
approaches on a wide range of tasks. Mastering transformers prepares you for
cutting-edge AI applications in industry and research.

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