Build your own Large Language Model

"A machine can have a large memory, but it cannot think - unless we teach it." - Alan Turing. Modern AI models such as GPT-4 or Llama are based on huge data sets and complex mathematical structures. But what is really behind them? In this article, we look at the key components needed to build a language model from scratch.


Large Language Models (LLMs) are neural networks trained on huge amounts of text. Their strength lies in the ability to generate human-like text, summarize content, and write code. At the core of these models is the Transformer architecture , which allows them to capture dependencies within texts and make contextual predictions.

Quantized weights compress the model particularly slimly, effectively overcoming hardware hurdles. Knowledge distillation also reduces the model size: a large model transfers its knowledge to a more compact variant. Pruning removes redundant parameters, resulting in a slim, efficient architecture without having to sacrifice accuracy.

Masked Language Modeling can be used to increase semantic depth. The model reconstructs incomplete texts and thus understands industry-specific terms. Next Word Prediction can be used for industry-specific technical language. Before a model can be trained, the text must be converted into a form that neural networks can understand using tokenization , embeddings and byte pair encoding .

To compensate for the lack of industry-specific training data, transfer learning and artificial data augmentation are used. Lean feedforward modules and optimized embeddings adapt them to the industry-specific data. A key element of transformer models is the self-attention mechanism . Each token is weighted in relation to all other tokens in the sentence, making the context of a word clearer.

For example, a sentence like "The cat jumped on the table because it was hungry" can mean that "she" is the cat. The model recognizes such connections by assigning importance to each word. This helps it to better understand the context. The mechanism thus enables the model to learn complex dependencies and semantic meanings within a text.

Pre-trained models integrate internal knowledge. This combination increases data diversity and enables high model quality despite limited local data volumes. The performance of the AI models is evaluated using specific metrics: Weighted-F1 and Perplexity measure the quality of text processing tasks, while response time and error rate transparently show the practical suitability.

Continuous adaptation to dynamic regulatory frameworks is achieved through constraint learning , which, for example, integrates data protection guidelines directly into the AI model using differential privacy . An adaptable set of rules and domain-specific fine-tuning processes allow for flexible and rapid response to new regulations.

The first step in the training process of a language model is pre-training . This involves feeding the model huge amounts of unstructured text to learn general language patterns, sentence structures and word meanings. During this process, the model tries to predict the next words in a sentence without focusing on a specific task. This creates a kind of universal language understanding.

Fine-tuning is the second step in which the pre-trained model is specialized for a specific task. It is trained with smaller, more specific data sets, for example to answer customer inquiries, classify texts or create summaries. Fine-tuning ensures that the model provides more precise and contextual answers for a defined application area.

Training an LLM requires a lot of computing power. To make the process more efficient, various optimization methods can be used. For example, model weights can be saved and loaded later, or pre-trained, published parameters can be downloaded. LoRA (Low-Rank Adaptation) is also used for fine-tuning with less computing effort.

An online learning loop is used for continuous development and adaptation to new findings and requirements. This continuously monitors model performance, analyzes new data and user feedback, and automatically adapts the model if necessary. Data protection and efficiency are ensured by differential privacy techniques and the removal of unnecessary connections .

A custom Python script can efficiently train a language model. It can also load external weights from a pre-trained model, optimizing the model for a specific task by adapting it to specific data. After training is complete, the script saves the updated weights so they are available for future use.

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Language models have already revolutionized many industries, from customer service to content creation. Through targeted pre-training and fine-tuning, models can be adapted for a wide variety of tasks. Those who develop a deeper understanding of these processes can create their own customized AI solutions and actively shape technological progress.

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