Introduction to Transformers

Machine learning model from Google Brain.

Transformers are a type of model architecture introduced in the paper "Attention is All You Need" by Vaswani et al. They have since revolutionized the field of natural language processing and have found applications in various other domains, including recommender systems.

Understanding the Concept of Transformers

Transformers are based on the concept of self-attention, also known as intra-attention. This mechanism allows the model to weigh the importance of different inputs differently, thereby focusing more on the relevant parts of the input data. This is particularly useful in tasks such as language translation, where the context of a word can greatly influence its meaning.

The Architecture of Transformers

The Transformer model consists of two main components: the encoder and the decoder.

The encoder takes in the input data and transforms it into a sequence of continuous representations. These representations are then passed on to the decoder, which generates the output one element at a time. Each element in the output sequence is generated by considering the entire input sequence and the elements of the output sequence generated so far.

Both the encoder and the decoder are composed of a stack of identical layers, with each layer consisting of two sub-layers: a self-attention layer and a position-wise fully connected feed-forward network. There is a residual connection around each of the two sub-layers, followed by layer normalization.

Self-Attention Mechanism in Transformers

The self-attention mechanism is the heart of the Transformer model. It allows the model to focus on different parts of the input sequence when generating each element of the output sequence. This is achieved by computing a weighted sum of the input elements, where the weights are determined by the attention scores.

The attention scores are computed using a softmax function, which ensures that they sum up to one. This allows the model to distribute its attention over the input sequence, focusing more on the relevant parts and less on the irrelevant parts.

Positional Encoding in Transformers

Unlike recurrent neural networks, Transformers do not have any inherent notion of the order of the elements in the input sequence. To overcome this limitation, Transformers use positional encoding to inject information about the position of the elements in the sequence.

The positional encoding is added to the input embeddings before they are fed into the encoder. This allows the model to learn and use the order of the elements in the sequence, which is crucial for many tasks.

In conclusion, Transformers are a powerful model architecture that leverages the self-attention mechanism to focus on the relevant parts of the input data. Their ability to handle long sequences and their parallelizability make them an excellent choice for many tasks, including recommender systems.