Questions tagged [notation]

Notation refers to a specific way of writing various concepts, functions, etc. Usually it is introduced to abbreviate complicated expressions and make common idioms more readable.

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What types of matrix multiplication are used in Machine Learning? When are they used?

I'm looking at equations for neural networks and backpropagation and I see this symbol in the equations, ⊙. I thought matrix multiplication of neural networks always involved matrices that matched ...
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Formal math notation of masked vector

I'm struggling to write my algorithm in a concise and correct way. The following is an explanation for an optimizer's update step of part of a vector of weights (not a matrix in my case). I have a ...
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Notation for features (general notation for continuous and discrete random variables)

I'm looking for the right notation for features from different types. Let us say that my samples as $m$ features that can be modeled with $X_1,...,X_m$. The features Don't share the same distribution (...
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117 views

Layer notation for feed forward neural networks

Apologies in advance, for I have a fairly rudimentary question on the notations for studying Feed-Forward Neural Networks. Here is a nice schematic taken from this blog-post. Here $x_i = f_i(W_i \...
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145 views

What does the pair of vertical lines in empirical entropy formula mean?

I am learning from this post. $\alpha$ is the ratio of the first subset, $$\alpha=\frac{\left|D_{1}\right|}{\left|D\right|}$$ according to the context and code of the post, $\left|D\right|$ means ...
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Meaning of equation for CNN probabilities

So the first equation above refers to a CNN (rather a committee of CNNs) for image classification. I am unable to understand exactly what the author is trying to do in the first equation. So far, I ...
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1answer
63 views

PAC Learnability - Notation

The following is from Understanding Machine Learning: Theory to Algorithm textbook: Definition of PAC Learnability: A hypothesis class $\mathcal H$ is PAC learnable if there exist a function $m_H : (...
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244 views

Does this notation mean vector-concatenation?

When reading papers on neural networks, I occasionally stumble upon the following notation with a semicolon: $$ \text{tanh}(\mathbf{W_c}[\mathbf{c}_t;\mathbf{h}_t]) $$ Unless otherwise noted, does ...
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Layer notation for convolutional neural networks

When reading about convolutional neural networks (CNNs), I often come across a special notation used in the community and in scientific papers, describing the architecture of the network in terms of ...
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92 views

Cannot see what the “notation abuse” is, mentioned by author of book

From Sutton and Barto, Reinforcement Learning: An Introduction (second edition draft), in equation 3.4 of page 38. The probabilities given by the four-argument function p completely characterize ...
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Why is an activation function notated as “g”?

In many cases an activation function is notated as g (e.g. Andrew Ng's Course courses), especially if it doesn't refer to any specific activation function such as ...
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58 views

Pound notation in Summation

I was going through a paper comparing glove and word2vec. I came across the pound notation shown below. What does it mean when used like this? The link for paper is here