Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [notation]

Questions 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.

Before asking a question on the site, please check if you can find your answer in Earliest Uses of Various Mathematical Symbols or the book A History of Mathematical Notations.

Alternatively, a textbook or paper usually takes the time to explain the notation they're using; please remember to mention where you've seen the notation you are asking about.

12848 questions
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Meaning of mathematical operator that consists of square brackets with a plus sign as a subscript

I was reading a paper on tomographic reconstruction, and I found an operator that is not explained: $[expression]_+$ The operator was used to compute a surrogate for the log-likelihood cost function. I do not know what that operator means. I've…
Damian
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Why not write $\sqrt{3}2$?

Is it just for aesthetic purposes, or is there a deeper reason why we write $2\sqrt{3}$ and not $\sqrt{3}2$?
Gelo Jacamile
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Mathematical symbol for "and"

I have found some pretty complete lists (I think) of mathematical symbols here and here, but I don't see a symbol for the word "and" on either list. A person could easily just write the word "and" or use an ampersand, but I was wondering if there…
ubiquibacon
  • 775
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What does the symbol := mean in mathematics?

What does the symbol := mean in mathematics? for example, C(continuum) := |R|
user350509
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6 answers

Is there a difference between $y(x)$ and $f(x)$

Oftentimes functions described by $f(x) = 2x+4$, and when this is mapped to the Cartesian plane, $f(x) = y$. This surely implies that $y = 2x+4$. Is there a difference between this and $y(x) = 2x+4$?
Frank Vel
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2 answers

Notation for: all subsets of size 2

How would one denote the set of all subsets of $A$ which have size $2$? Would $$\binom{A}{2}$$ be a good idea?
stefan
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What does this "subset" symbol mean?

I just came across this "subset" symbol in a PDF: $$\Omega \subsetneq T$$ I've never seen it before, and I tried looking for it via Detexify (to no avail). What does it mean?
gablin
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2 answers

Equivalent to proportionality sign for additive constants

Short question Is there an equivalent to the proportionality sign $\propto$ for additive constants? The proportionality relation $y\propto x$ implies that $y=kx$ for some constant $k$. Is there a shorthand to express that $y=x+k$ for some constant…
Till Hoffmann
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Mathematical Notation - Arrow Sign

What does the $\Rightarrow$ arrow mean when showing working out in maths? How do we use it appropriately?
confused
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What is $\gtrless$?

I'm reading Papadimitriou & Steiglitz's Combinatorial Optimization and came across notation I'd never seen before and don't know what it means. The $\LaTeX$ markup for it is \gtrless ($\gtrless$), which took me quite a while to find. It arises in…
JasonMond
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Notation: Is $(\Delta x)^2 = \Delta x^2$?

I read this in a book and was wondering whether it's valid or not: I thought $\Delta x^2$ would mean 'change in $x^2$', which would be quantitatively different to $(\Delta x)^2$; no?
Luke Collins
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What does "$f\in C^2[a,b]$" mean?

What does this expression mean? $$f\in C^2[a,b]$$ More specifically, I don't know what $C$ means.
Tomas Sironi
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A pedantic question about notation -- "such that" symbols

I've seen a few different symbols for "such that" in my studies, including these four: $$ \ni \quad\quad \:\cdot\ni\cdot\: \quad\quad \colon \quad\quad \mid $$ I'm aware that either of the last two are acceptable in set notations, e.g.…
bjd2385
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Does anyone use $\subset$ for proper subset anymore?

I belong the the group of people who still write (not necessarily proper) subset as $\subseteq$ to avoid any confusion with proper subset, which I notate $\subsetneq$; I usually do not use $\subset$ at all. But now that I think about it, I have not…
Gaussler
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Symbols for "odd" and "even"

Let $A$ be a sequence of letters $\langle a,b,c,d,e,f \rangle$. I want to create two subsequences, one with the values with odd index and other with the values with even index: $A_\mathrm{odd} = \langle a,c,e \rangle$ and $A_\mathrm{even} = \langle…
user194174
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