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.
Questions tagged [notation]
16 questions
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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 dimensions on both sides, such as... [3, 3]@[3, 2].…
Ant
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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 (i.e. some categorical, some numerical, etc.).…
Yael M
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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 layers. However, I was not able to find a paper or…
Czechnology
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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 sigmoid.
However, where does this convention come from? And for what reason did g…
Blaszard
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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 vector $\alpha \in \mathbb{R}^d$, and a set $S$ that…
leed
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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
Sagar Patel
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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 $x_i = f_i(W_i \cdot x_{i-1})$ where $f_i$ is the activation…
Pavithran Iyer
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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 the number of samples?
What are the pair of…
Jay
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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 $m_H : (0, 1)^2 \rightarrow \mathbb{N}$ and a learning…
tkj80
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Explain notation in Bishop Eq 1.60
I'm starting to work through Bishop's "Pattern Recognition and Machine Learning" book, and have run into unfamiliar notation.
Eq. 160 is prefaced by saying "For this purpose, we shall assume that, given the value of $x$, the corresponding value of…
Jolyon
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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 think they're calculating the index of max…
Stormlight
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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 this by default mean the following:
vector…
Kari
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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 the dynamics of a
finite MDP. From it, one can…
cinqS
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What is meant by this notation for ensemble classifier error rate
The below is a picture which denotes the error of an ensemble classifier. Can someone help me understand the notation
What does it mean to have (25 and i) in brackets and what is ε^1 is it error of first classifier or the error rate raised to power…
Arun Jose
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Probability notation q(y) and q(Y) and its implication to vector functions
The function in question is (from Appendix B, Proof of proposition 2.1 from Posterior Regularization for Structured Latent Variable Models):
$$q(\textbf{Z}) = \frac{p_{\theta}(\textbf{Z}|\textbf{X})exp(\lambda^T \cdot…
Martin G
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