# Tagged Questions

Question on the meaning, history, and usage of mathematical symbols and notation. Please remember to mention where (book, paper, webpage, etc.) you encountered any mathematical notation you are asking about.

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### What “double bracket” means? [duplicate]

What does this symbol mean? Please i need help: Its the symbol just before "$H^{t-1}$". Thanks for help
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### What is the double bracket notation used here?

Its kind of a bracket but I'm not sure what it means. I have two ideas about it: It means the number of times the expression in satisfied or it changes for $1$ or $0$ depending on the result every ...
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### Notation: What does this summation mean?

I need to understand what the summation below mean. I specifically do not understand the $i<j$ below the summation. $$\sum_{\substack{ i<j}}^{N} d_{ij}$$ Insight about the equation There ...
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### Notation for where two variables cannot both simultaneously take a specific value

I am building a set of values A, containing coordinates ($B_{x,y}$), where $x$ and $y$ take any of the following values: $x$ := {-2,-1,0,1,2} and $y$ := {-1,0,1} The catch is that both $x$ and $y$ ...
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### Mathematical notation for redefined set?

I have a set of numbers (W), from which I am only keeping those greater than 5. I want to state that the set W has been redefined to only include the subset of values greater than 5, but want to ...
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### Random math questions (modular arithmetic & notation)

I found this amazing wall clock picture on the internet but I really don't know a few things. I don't know what's $B'_L$, &#x33;, why $2^{-1}\equiv 4[7]$ and ...
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### $O_{\mathcal{S}'\rightarrow \mathcal{S}}(h^\infty)$

What does the notation: $$O_{\mathcal{S}'\rightarrow \mathcal{S}}(h^\infty)$$ mean in Zworski's semiclassical analysis? (To be clear, I know what $O(h^\infty)$ means in the context of normed and ...
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### Why is the Jacobian matrix the transpose of what I would think it'd be/usefully be (total derivative is a synonym) (EDIT: I was a total wally)

I'm sorry this isn't a yes/no/am-I-right question but I seriously cannot see why the Jacobian/total derivative matrix is what it is? I am also using it as LaTeX practice (for maths) hence the barely ...
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### Notation for the set of real numbers

I've seen R used for the set of reals, and also a hollow R, but I seem to remember an elegant copperplate cursive R. Is this correct? Can I use this R? Handwritten, going cursive seems to be clearer. ...