The Transformer model has been gaining considerable traction in the field of deep learning and deep neural networks in recent years, owing to its efficacy for natural language processing. This methodology has been particularly advantageous for Google, allowing them to refine their search engine results more effectively.
Over the past three years since its 2017 launch, the Transformer deep learning model architecture has seen increasing application across an ever-widening array of disciplines. Time series forecasting is one area in particular in which this methodology has been found to be particularly effective.
The research community is continually exploring new applications for Transformers and developing innovative ways to use them. In this synopsis, we will discuss the fascinating features of Transformers and then provide a definition of the Transformer model.
The Transformers model, please.
Transformer networks are Artificial Intelligence (AI) models that are able to gain knowledge and understanding through the examination of data in a sequential manner. To develop these models, researchers rely on a range of innovative and ever-evolving mathematical techniques known as attention or self-attention. This data collection process is instrumental in ascertaining how far-reaching data points are connected and how they rely on one another.
In 2017, Google published a research paper which demonstrated the implementation of Transformers as one of the most advanced models ever constructed. Since then, the application of Transformer Artificial Intelligence (AI) in the realm of Machine Learning has seen a significant surge in development.
According to a report published in August 2021, researchers from Stanford University have already identified Transformer-based models as the “foundational models” for their work in the field of artificial intelligence. This report is evidence of the increasing significance of Transformer-based models in AI development, as researchers are now relying on them as the fundamental building blocks for their research.
In recent years, researchers have noticed a dramatic increase in the size and complexity of foundation models. This has caused them to remark that the sheer magnitude and breadth of foundation models over the past few years has opened up a new field of possibilities. This development has been so unexpected that it has left us with an expansive vision of what is now achievable.
Architecture outline for a model of a transformer
Due to its attention mechanism, transformers are similar to the encoder-decoder design of recurrent neural networks (RNNs). In other words, transformers are capable of performing sequence-to-sequence (seq2seq) operations while removing the sequential component.
When compared to an RNN, a Transformer can be trained more quickly since it can analyse input in parallel.
This diagram depicts the general structure of the Transformer deep learning model. The Transformer consists of two primary parts:
- The encoder stacks, which consist of Nx layers of identical encoders (Nx = 6 in the original publication).
- Layers of identical decoders, or “decoder stacks” (Nx = 6 in the original work).
Due to the fact that neither recurrent neural networks nor convolutions were included in the models, positional encoding was added between the encoder and decoder stacks in order to take advantage of the inherent sequence order.
Encoder for Transformers
The encoder has N levels, each of which has two sublayers; the first sublayer is responsible for generating self-attention via a multi-head process.
Research has demonstrated that multiple-head mechanisms are capable of producing a single, unified output by applying linear projections of queries, keys, and values to generate h distinct outputs simultaneously.
The second layer of our model utilises a fully connected feed-forward neural network, incorporating Rectified Linear Units (ReLUs) for activation. This layer is composed of two linear transformations.
The Transformer encoder employs six levels which sequentially process each word in the input sequence. The weight parameters (W1, W2) and bias parameters (b1, b2) are shared across layers, though they are distinct for each individual layer.
Furthermore, each of the sublayers is encompassed by a residual connection. To ensure consistency in the total calculation between the input of the sublayer, denoted by X, and the output of the sublayer, a normalisation layer, denoted as layernorm(.), is incorporated into each sublayer (X).
Because the Transformer deep learning architecture doesn’t use recurrence, it can’t figure out where words are located in a sentence on its own.
Position encoding has been incorporated into the embeddings by utilising sine and cosine functions of varying frequencies to create positional encoding vectors of equivalent dimensions to the input embeddings. Subsequently, the positional information is injected by adding the output embeddings to the input embeddings.
The decoder for Transformers
Encoder and decoder functions are comparable in a number of ways. Each of the N = 6 functional levels of a decoder is divided into three sublayers.
- The decoder stack gets the prior output in the first sublayer, from which it supplies positional data and applies self-attention to all of the heads.
In contrast to encoders that focus on individual words independently of surrounding words, decoders are attentive to the context of the previous words. Consequently, the word at position I can only be accurately predicted based on the words that have come before it.
The values calculated by multiplying the quantities Q and K by a scale factor are obfuscated by the implementation of a multi-head attention mechanism, which involves the simultaneous execution of multiple single attention functions.
- In the second sublayer of the encoder, we observe the presence of a multi-head self-attention algorithm, which is identical to the one present in the first sublayer. Apart from being provided with the output keys and values from the encoder, the decoders also obtain inquiries from lower-level decoders through this multi-head system.
- The decoder may pay attention to individual words in the input sequence. In the third layer, a fully connected feed-forward network is created that is analogous to the second sublayer of the encoder.
Following the implementation of the three sublayers of the decoder, a normalising layer is employed. The residual connections between the decoder and the other layers remain intact. Furthermore, the decoder, like the encoder, incorporates positional encodings into the input embeddings.
Transforming neural networks: what exactly is it?
It is widely acknowledged that Transformer architectures are indispensable for neural networks that are used to analyse various types of data, such as text, genomic, audio and time series data. The most common application of Transformer neural networks is in the area of Natural Language Processing.
A Transformer neural network is capable of encoding and decoding a sequence of vectors into and from their original form. An essential component of the Transformer is its attention mechanism, which allows for the relative relevance of each token to other tokens in the input to be determined. This attention mechanism is of critical importance in the Transformer algorithm.
The Transformer architecture makes use of an attention mechanism, which allows it to take into account all the relevant words to determine the appropriate gender for ‘it’ in French or Spanish in a machine translation model. By making use of the attention mechanism, the word transformer is able to analyse the words surrounding the target word and accurately determine how to best translate it.
Note: A Transformer network may be used in lieu of traditional RNNs, LSTMs, and gated recurrent networks (GRUs).
Architecture of a Neural Network for a Transformer
An input phrase is split into two sequences using a neural network called a “Transformer.”
- A series of word vector embeddings
- Input sequence for position encoding
As the use of word vector embeddings as a numerical representation of text is becoming increasingly widespread, it is becoming clear that neural networks are unable to interpret words without first being converted into embedding representations.
In the embedding format, dictionary words are represented as vectors of numerical values that capture the properties of the words. Position encodings are added to these vectors to indicate the location of a word within the source text. These combined embeddings and encodings are then processed by a Transformer. The output of the Transformer is then sent to a sequence of encoders and decoders for further processing.
In contrast to the TNN (Transmission Neural Network) which receives all of its input at once, RNNs (Recurrent Neural Networks) and LSTMs (Long Short Term Memory) obtain their input in a sequential manner. During the encoding process, each encoder alters its input signal into an alternative set of vectors.
Decoding is the inverse of encoding, which involves taking encoded information and transforming it back into words and phrases in a natural language. The softmax function can be used to calculate the probability of each word or phrase, and then select the most likely outcome. This process allows for the creation of phrases in a natural language with a certain degree of accuracy.
Every decoder and encoder in a system is accompanied by an attention mechanism, which allows for the individual processing of a single input word by taking into account the relevant information contained within the other words in the sequence, while simultaneously hiding away any words that don’t contain pertinent data.
The utilisation of parallel processing on graphics processing units allows for various attention methods to be implemented simultaneously. This is enabled by the reliable GPU, which provides the capacity for parallel processing. To maximise this benefit, it is possible to run multiple attention mechanisms concurrently. This practice is referred to as a “multi-head attention mechanism”.
In comparison to LSTMs and RNNs, the Transformer deep learning model has the distinct benefit of being able to handle numerous words at once.
Network with feedforward connections
Following the utilisation of the attention vectors, a feed-forward neural network is employed. This process prepares the attention vectors to be used in the subsequent encoder or decoder layer.
The feed-forward network has the distinct advantage of being able to process only one attention vector at a time. This is a marked contrast with the recurrent neural networks (RNNs) which are dependent upon each other. This independence of the attention vectors is essential and makes a significant difference when parallelism is necessary.
The Transformer deep learning model can carry out the following.
Spreading focus across many brains
Multi-head attention can be viewed as a form of multitasking, enabling the Transformer deep learning model to predict the next word in a sequence using a single word as an input. Through this mechanism, multiple different outcomes can be generated for the same input by utilising multiple concurrent calculations. The end result of this process is then fed into a SoftMax algorithm, which helps to identify the most accurate term.
Taking into account all the relevant factors, such as the tense of the word, the context of the text, and the type of word (verb, noun, etc.), SoftMax is able to make simultaneous calculations that result in the highest possible probability of finding the desired word.
Multi-head focus concealment
The multi-head attention technique is quite similar to the current one, however, the word decoder is not able to view what is present after the current word in the sequence. This lack of visibility restricts the Transformer’s ability to accurately learn from data and anticipate future occurrences.
Skip connections, also referred to as residual connections, are a type of connection that link one ‘Add and Norm’ layer to another without passing through the attention module. This type of connection can help prevent the network from deteriorating and can assist in keeping the gradients flowing consistently during the training process, thereby improving its effectiveness.
Reputable examples of the Transformers franchise
Transformers are a cornerstone of modern machine learning models, and they are widely employed in many of today’s leading applications. Examples include Google Translate, Microsoft Translator, and IBM Watson, which all use machine learning to convert human speech into written text. These models have achieved considerable success and are among the most popular in use today.
Google’s Bidirectional Encoder Representations from Transformers (BERT) is a method developed by Google to enable natural language understanding. It leveraged already-trained Transformers to accomplish this. Until 2020, almost all English-language Google searches utilised BERT.
Both GPT-2 and GPT-3
Generative Pre-trained Transformer (GPT) technology symbolises the next two generations of pre-trained generative models in the field of Artificial Intelligence (AI). GPT is an open-source tool that is used to carry out a variety of Natural Language Processing (NLP)-related tasks such as machine translation, question answering, text summarization, and more. This technology provides developers and researchers with a powerful tool to make advances in the field of AI.
The key distinguishing factor between GPT-2 and its successor, GPT-3, lies in the magnitude of construction. GPT-3 boasts a significant improvement over GPT-2 in a number of key aspects, the most significant of which is its ability to handle an impressive 175 billion machine learning parameters, in comparison to GPT-2’s 1.5 billion.
The Transformer’s Weaknesses
We found that the Transformer deep learning model significantly outperformed RNN-based seq2seq models. However, it does have certain restrictions:
- It is essential to bear in mind that there is a maximum number of characters that can be handled by the attention-based system. Consequently, the text must be broken down into distinct segments before it can be fed into the system.
- The consequences of breaking up chunks of text into smaller pieces can lead to a lack of context, making it difficult to comprehend the overall message. It is important to remember that when phrases are split in the middle, their meaning can be distorted. As a result, any grammatical or semantic structure that existed in the original text is lost in the fragmented version.
The meaning of “attention”
In recent years, there has been an increased amount of research conducted on the attention mechanism, particularly in regards to how it is employed in sequential tasks. To gain a better understanding of how the attention mechanism works, it is important to consider how it dynamically assigns weights to the items in a sequence based on the queries and keys being utilised to access them.
Through the utilisation of this technique, we are able to compute an average over numerous variables quickly and with ease. However, we must adjust the weighting of certain elements based on their relative significance. Ultimately, we need to prioritise certain inputs over others and this can be accomplished through the use of dynamic selection. In order to make this possible, there are four components of the attention mechanism which must be determined.
- Query: The query specifies what we are looking for or what we could be paying attention to in the sequence.
- Keys: Vectors are associated with the items and keys used as input. This feature vector describes the characteristics of the element and the point at which it is able to operate effectively. In order to identify the parts of a query that require particular attention, it is necessary to create keys which can help us to locate them.
- Values: We also have value vectors in addition to the input items. The purpose of this exercise is to produce a mean value of these feature vectors.
- Method of Calculating scores: By making use of the scoring function, we can accurately identify the areas that require our immediate attention. The scoring function takes a query and key as inputs and produces a score, which indicates the level of attention that should be given to the query-key combination.
A dot product or a lightweight MLP (Multi-layer Perceptron) for comparing similarity metrics is the most frequent method of implementation.
A definition of sequence models, please. An Overview
It is undeniable that all occurrences in our lives are predetermined by either our decisions or our environment. Patterns are evident virtually everywhere we look. A sequence can be defined as an arrangement of events that follows a logical order. This concept applies to language as well; each sentence follows a set structure in order to effectively convey meaning. Essentially, words are arranged in a particular manner to form a cohesive statement.
It is particularly pertinent to leverage sequence models when dealing with deep learning, as sequences tend to be recurrent within datasets. The presence of additional highly correlated attributes, as well as our expectations from the model, are the key considerations when making the decision to use a sequence model or not.
Utilising sequence models, we are able to explore the chronological arrangement of occurrences and the interaction between their components. Consequently, we are more capable of forecasting the sequence ahead. Before the invention of Transformers, Recurrent Neural Networks (RNNs), Long Short-Term Memory Networks (LSTMs), and Gated Recurrent Units (GRUs) were the most prevalent architectures for such models.
Despite impressive results and widespread acceptance, traditional deep learning models have their limitations. Specifically, these models often fail to pick up on long-distance relationships within sequences, making it difficult for them to retain the correct context. In response to such issues, as well as to the increasing demand for quick responses, researchers have come up with the concept of “Attention”. Additionally, self-awareness is a key component of Transformers as well. To gain a better understanding of these concepts, one should consider studying the paper “Attention Is All You Need”.
Transformer-based reinforcement learning
Reinforcement learning is a technique in which the system rewards users for taking successful corrective actions to achieve a difficult goal. This incentivization-based approach reinforces the positive outcomes of making the right choices and has been proven to be effective. In terms of Transformer Reinforcement Learning, Long Short-Term Memory (LSTM) is the most widely used and efficient method.
Despite the fact that Transformers are most commonly used for reinforcement learning exercises, they have also proven to be highly effective for natural language processing (NLP) tasks, such as those undertaken by the Generative Pre-trained Transformer (GPT) and Bidirectional Encoder Representations from Transformers (BERT). Through the application of Transformers to NLP, sequence-to-sequence problems can be effectively addressed and long-range dependencies managed.
When it comes to completing tasks within the allotted timeframe, the Markov method of reinforcement learning is the preferred approach. This method involves utilising a sequence model to identify the sequences of actions which will yield the highest rewards. In doing so, it provides an effective way to optimise the decision making process and ensure tasks are completed in accordance with their due dates.
The development of effective Transformer reinforcement learning solutions may be significantly improved through the use of models that have high capacity and computational power and that can be easily adapted to other domains, such as natural language processing (NLP). This can enable the development of more powerful and efficient solutions that are better suited to a variety of tasks.
Recent research conducted by a team at the University of California, Berkeley has suggested that the use of more sophisticated Transformer topologies can facilitate reinforcement learning by treating it as a single, large sequence modelling problem. The proposed approach is based on the interplay between rewards and action distributions across a range of different states.
By removing the need for separate behavioural policy guidelines, the authors of the study “Reinforcement Learning as One Big Sequence Modelling Problem” (source) were able to simplify the process of making design decisions.
Therefore, we may use this method for a number of purposes, such as offline reinforcement learning and a variety of dynamics-related domains.
In this article, we examined the concept of sequential models, discussed the emergence of Transformer deep learning models after other sequential architectures, and explored why Transformer models have turned out to be the most beneficial.
Following our initial discussion, we delve into the details of the Transformer and its various applications. We review the most common ways these machines are utilised and explore the possibility of other use cases that might be beneficial. It is apparent that the Transformer is a dependable and reliable tool with a wide range of potential applications.