# Tag Info

42

Yes, indeed, neural networks are very prone to catastrophic forgetting (or interference). Currently, this problem is often ignored because neural networks are mainly trained offline (sometimes called batch training), where this problem does not often arise, and not online or incrementally, which is fundamental to the development of artificial general ...

19

For newbies, NO. Sentence generation requires sampling from a language model, which gives the probability distribution of the next word given previous contexts. But BERT can't do this due to its bidirectional nature. For advanced researchers, YES. You can start with a sentence of all [MASK] tokens, and generate words one by one in arbitrary order (instead ...

16

Yes, the problem of forgetting older training examples is a characteristic of Neural Networks. I wouldn't call it a "flaw" though because it helps them be more adaptive and allows for interesting applications such as transfer learning (if a network remembered old training too well, fine tuning it to new data would be meaningless). In practice what you want ...

13

Even if it’s impossible to answer this question properly, as non trivial is not well defined (maybe the author will edit this questions later, to specify it better), I take the opportunity to point out this paper which looks interesting to me Smallest Neural Network to Learn the Ising Criticality Assuming you have a general idea of the Ising Model I think ...

9

Should I be changing the weights/biases on every single sample before moving on to the next sample, You can do this, it is called stochastic gradient descent (SGD) and typically you will shuffle the dataset before working through it each time. or should I first calculate the desired changes for the entire lot of 1,000 samples, and only then start ...

9

3D CNN's are used when you want to extract features in 3 Dimensions or establish a relationship between 3 dimensions. Essentially its the same as 2D convolutions but the kernel movement is now 3-Dimensional causing a better capture of dependencies within the 3 dimensions and a difference in output dimensions post convolution. The kernel on convolution ...

9

In a neural network (NN), a neuron can act as a linear operator, but it usually acts as a non-linear one. The usual equation of a neuron $i$ in layer $l$ of an NN is $$o_i^l = \sigma(\mathbf{x}_i^l \cdot \mathbf{w}_i^l + b_i^l),$$ where $\sigma$ is a so-called activation function, which is usually a non-linearity, but it can also be the identity ...

9

tl;dr I always like to think of Neural Networks as a generalization of logistic regression. I too don't like that, traditionally, when introducing Neural Networks, books start with biological neurons and synapses, etc. I think its more beneficial to start from statistics and linear regression, then logistic regression and then neural networks. A ...

8

I agree that this is too broad, but here's a 1 sentence answer for most of them. The ones I left out (from the bottom of the chart) are very modern, and very specialized. I don't know much about them, so perhaps someone who does can improve this answer. Perceptron: Linear or logistic-like regression (and thus, classification). Feed Forward: Usually non-...

7

This is basically reinforcement learning. The state space contains your moves, and the value function are the value you store at the end. And your rewards are the end results. And you have episodic game. It is an AI method. Consider looking at value iteration, policy iteration, SARSA, Q-learning. The difference between neural network method and yours is you ...

7

Actually, the cross-entropy loss function would be appropriate here, since it measures the "distance" between a distribution $q$ and the "true" distribution $p$. You are right, though, that using a loss function called "cross_entropy" in many APIs would be a mistake. This is because these functions, as you said, assume a one-hot label. You would need to use ...

6

There is an assumption behind the theory training a neural network, or using any piece-wise learning method, that a training sample is representative of the data set as a whole - that it has been sampled fairly from the population that the learning algorithm has been set up to approximate. The term i.i.d. stands for "independent and identically distributed"...

6

The related ACM article describes a few specific technical contributions, which led the ACM to award them. Geoffrey Hinton Backpropagation: In a 1986 paper, "Learning Internal Representations by Error Propagation", co-authored with David Rumelhart and Ronald Williams, Hinton demonstrated that the backpropagation algorithm allowed neural nets to ...

6

You could say that NAS fits into the domain of Meta Learning or Meta Machine learning. I've pulled the NAS papers from my notes, this is a collection of papers/lectures that I personally found very interesting. It's sorted in rough chronological descending order, and *** means influential / must read. Quoc V. Le and Barret Zoph are to good authors on the ...

6

The auto-encoder (AE) can be used to learn a compressed representation (a vectorised hash value) of each observation in the training dataset, $z$, which can then be used to later retrieve the original (or similar) observation. The variational auto-encoder (VAE), a statistical variation of AE, can also be used to generate objects similar to the observations (...

6

Since a neural network does iteratively learn its own weights I assume you mean the structure of the neural network - the number of layers and nodes per layer. If what I said above was your question, then yes, it most definitely is being explored. Even when a neural network is allowed to learn its own structure it still needs to be suited to a specific ...

6

Let's suppose that we have an MLP with $15$ inputs, $20$ hidden neurons and $2$ output neurons. The operations performed are only in the hidden and output neurons, given that the input neurons only represent the inputs (so they do not perform any operation). Each hidden neuron performs a linear combination of its inputs followed by the application of a non-...

6

If what you are asking is what is the intuition for using the derivative in backpropagation learning, instead of an in-depth mathematical explanation: Recall that the derivative tells you a function's sensitivity to change with respect to a change in its input. A high (absolute) value for the derivative at a certain point means that the function is very ...

6

I have an idea to find the optimal number of hidden neurons required in a neural network but I'm not sure how accurate it is. It's a complete non-starter, and there is a no such calculation possible in the general case (real-valued inputs to a neural network). Even with one input neuron it is not possible. That is because even with one input, the output ...

5

Recurrent neural networks (RNNs) are artificial neural networks (ANNs) that have one or more recurrent (or cyclic) connections, as opposed to just having feed-forward connections, like a feed-forward neural network (FFNN). These cyclic connections are used to keep track of temporal relations or dependencies between the elements of a sequence. Hence, RNNs ...

5

Yes, this is an active area of research as we speak. Both using classic algorithms (decision trees, random forests, Bayesian ensembles) as well as neural networks. This can also be done via evolutionary algorithms. I have personally used them for hyperparameter tuning in a few cases where squeezing out a couple of extra points of accuracy was key. This is ...

5

$g(x) = x^2$ is indeed a parabola and thus has just one optimum. However, the $\text{MSE}(\boldsymbol{x}, \boldsymbol{y}) = \sum_i (y_i - f(x_i))^2$, where $\boldsymbol{x}$ are the inputs, $\boldsymbol{y}$ the corresponding labels and the function $f$ is the model (e.g. a neural network), is not necessarily a parabola. In general, it is only a parabola if $... 5 All CNNs can be represented as vanilla networks on the flattened image data. Just to do so, you would need A LOT of parameters (most of which would be 0) for what CNNs do freely. You can think of a CNN as reusing a filter on a masked input (whichever receptive field it's looking at whatever point during the convolution) repetitively. In other words, fully ... 5 3D convolutions should when you want to extract spatial features from your input on three dimensions. For Computer Vision, they are typically used on volumetric images, which are 3D. Some examples are classifying 3D rendered images and medical image segmentation 5 Neuroevolution Through Augmenting Topologies or NEAT may be what you are referring to. The original paper by Kenneth O. Stanley is here NEAT combines a neural network and a genetic algorithm. Instead of using back propagation or gradient descent to "train" your network, NEAT creates a population of very simple neural networks (no connections) and evolves ... 5 This problem is called exploding gradients, resulting in an unstable network that at best cannot learn from the training data and at worst results in NaN weight values that can no longer be updated. One way to assure it is exploding gradients, is if loss is unstable and not improving, or if loss shows NaN value during training. Apart from the usual ... 5 Let us suppose we have a network without any functions in between. Each layer consists of a linear function. i.e layer_output = Weights.layer_input + bias Consider a 2 layer neural network, the outputs from layer one will be: x2 = W1*x1 + b1 Now we pass the same input to the second layer, which will be x3 = W2x*2 + b2 Also x2 = W1*x1 + b1 Substituting ... 5 The loss function used is the triplet loss function. Let me explain it part by part. Notation The$f^a_i$means the anchor input image. The$f^p_i$means the postive input image, which corresponds to the same people as the anchor image. The$f^n_i$corresponds to the negative sample, which is a different person(input image) then the anchor image. The ... 5 Dropout only ignores a portion of units during a single training batch update. Each training batch will use a different combination of units which gives them the best chance of that portion of them working together to generalize. Note the the weights for each unit are kept and will be updated during the next batch in which that unit is selected. During ... 5 It depends on the architecture of the neural network. However, in general, no, neurons at layer$l$are not only affected by neurons at layer$l-1$. In the case of a multi-layer perceptron (or feed-forward neural network), only neurons at layer$l-1$directly affect the neurons at layer$l$. However, neurons at layers$l-i$, for$i=2, \dots, l\$, also ...

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