Contents

- 1 What is Adagrad algorithm?
- 2 What is the problem with Adagrad?
- 3 Is Adagrad momentum based?
- 4 What does Adadelta mean?
- 5 What is the difference between RMSProp and momentum?
- 6 What is Adamax Optimizer?
- 7 What is the update rule for AdaGrad and Adadelta?
- 8 Where did the idea of AdaGrad come from?
- 9 What are the drawbacks of the AdaGrad method?
- 10 Is the AdaGrad algorithm immune to η selection?

## What is Adagrad algorithm?

Adaptive Gradient Algorithm (Adagrad) is an algorithm for gradient-based optimization. It performs smaller updates As a result, it is well-suited when dealing with sparse data (NLP or image recognition) Each parameter has its own learning rate that improves performance on problems with sparse gradients.

## What is the problem with Adagrad?

The problem of AdaGrad, however, is that it is incredibly slow. This is because the sum of gradient squared only grows and never shrinks. RMSProp (for Root Mean Square Propagation) fixes this issue by adding a decay factor. More precisely, the sum of gradient squared is actually the decayed sum of gradient squared.

## Is Adagrad momentum based?

Adagrad (Adaptive Gradient Algorithm) In Adagrad optimizer, there is no momentum concept so, it is much simpler compared to SGD with momentum. The idea behind Adagrad is to use different learning rates for each parameter base on iteration.

## What does Adadelta mean?

An Adaptive Learning Rate Algorithm (AdaDelta) is a Gradient Descent-based Learning Algorithm that uses the exponential decay rate of the first- and second-order moments. AKA: AdaDelta, AdaDelta Optimizer, AdaDelta Algorithm. Example(s):

## What is the difference between RMSProp and momentum?

While momentum accelerates our search in direction of minima, RMSProp impedes our search in direction of oscillations.

## What is Adamax Optimizer?

Adamax class Optimizer that implements the Adamax algorithm. It is a variant of Adam based on the infinity norm. Default parameters follow those provided in the paper. Adamax is sometimes superior to adam, specially in models with embeddings.

## What is the update rule for AdaGrad and Adadelta?

The update rule for ADAGRAD is as follows: Δxt = − η √ ∑t τ = 1g2 τgt (5) Here the denominator computes the l2 norm of all previous gradients on a per-dimension basis and η is a global learning rate shared by all dimensions. While there is the hand tuned global learning rate, each dimension has its own dynamic rate.

## Where did the idea of AdaGrad come from?

These ideas date back to 50’s; look for the DFP method, the BFGS method and the Dennis and More analysis. The AdaGrad algorithm is just a variant of preconditioned stochastic gradient descent, where B B is cleverly selected and updated regularly, and the gradient calculation follows SGD.

## What are the drawbacks of the AdaGrad method?

The idea presented in this paper was derived from ADAGRAD in order to improve upon the two main drawbacks of the method: 1) the continual decay of learning rates throughout training, and 2) the need for a manually selected global learning rate. The second drawback is quite self-explanatory.

## Is the AdaGrad algorithm immune to η selection?

This also justifies that AdaGrad is kind-of immune to the η η selection: after a few iterations, the weights from the gradient calculation in B B pay-off. AdaGrad vs. plain Gradient Descent with carefully selected step size.