Estimativa de Momento Adaptativa, comumente conhecida como Adam, é um método avançado algoritmo de otimização widely used in treinar modelos de aprendizado de máquina, particularly in aprendizado profundo. Introduced in 2014 by D.P. Kingma and J.B. Ba, Adam combines the ideas of two other popular otimização de modelos: Momentum and RMSProp.
A principal vantagem do Adam é sua capacidade de ajustar de forma adaptativa o taxa de aprendizado for each parameter based on the first and second moments of the gradients. This means that during training, Adam tracks both the average of the gradients (first moment) and the variance of the gradients (second moment). By doing so, it can make more informed updates to the model parameters, allowing for faster convergence and improved performance.
Adam usa duas hyperparameters, beta1 and beta2, which control the decay rates of the moving averages of the gradients and their squared values, respectively. Typically, beta1 is set to 0.9 and beta2 to 0.999. Another crucial parameter is epsilon, a small constant added to prevent division by zero during updates.
One of the key features of Adam is its robustness to noisy gradients and its efficiency in handling sparse data. This makes it particularly suitable for applications in processamento de linguagem natural, image recognition, and other fields where gradient noise is prevalent. Overall, Adam has become a go-to choice for many practitioners due to its simplicity and effectiveness in optimizing complex models.