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.

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How to write the multinomial theorem formula without the dots?

The multinomial theorem: $(x_1 + x_2 + \cdots + x_m)^n = \sum_{k_1+k_2+\cdots +k_m = n} {n \choose k_1, k_2, \ldots, k_m} x_1^{k_1} x_2^{k_2} \cdots x_m^{k_m}$ There are lots of dots here, and to be fancy and rigorous (one could rise the…
gaazkam
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Why is $y^2 = 4ax$ considered as the standard form of a parabola?

Was wondering why $y^2 =4ax$ is considered as the standard form of a parabola? I was going through my textbook and all important results like equation of Tangent, Normal, Chord of contact was given in terms of $y^2 = 4ax$ form. So is there any way…
Mahadev
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Confusion over set theory notation and finding the no. of even subsets

A question states, " Let $S$ be an even set, $\{1,2,3,4....n\}$ such that $n>2$. Let $S_1,S_2,\dotsc,S_n$ be even subsets of $S$" This implies there has to be some order of listing the subsets. What is that order? Also, For an even set of $n$…
satan 29
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What does the notation $x^+$ and $x^-$ mean?

I have been reading through this document, and on the bottom of page 7 it uses the notation $x(A) = x^+(A) - x^-(A)$ where $x$ is a function. What could this notation mean?
while1fork
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unfamiliar subset notation

While reading this paper (section 3.3) I came across an unfamiliar notation: "Given an expanded query set Q, we extract $Q_s |q_i \nsubseteq q_j|q_i,q_j \in Q_s $ " Here Q is a set of elements. Can someone please explain what the notation means? My…
Ashoka Lella
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Notation for the sum of the scores of items of an intersection of two sets

I have two sets of items. Every item has a score. I'm finding the sum of the scores of the items of the intersection of both sets. What would the best way to notate this be? An example: A = {a, b, c, d} B = {c, d, e} The scores are: a -> 9 b -> 8 c…
Max
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Is there notation for the larger of two sets by cardinality/size?

As the title says, suppose I have sets $X= \{ 1, 2, 3,10\}$ and $Y=\{199, 8\}$, then is there an accepted notation to choose $X$? Something like: $\max_{|\cdot|}(X, Y) = X$ ?
Luce
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What this notations mean (O-, Θ, Ω-)

I searched for this notations (O-, Θ, Ω-) but i don't know their job exactly, I just found their mean in greek language but i don't know what it's mean in math. I'm was reading about algorithms and their analysis, and author said that algorithms…
user483856
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What Is The Meaning of $\{\|X_{n}-Y_{n}\|>\varepsilon\}$?

Unfortunately I've forgotten some notation I came across recently. Can someone clarify what is the meaning of what is shown in the red box? The book is Probability Essentials by Jacod-Protter.
Cure
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How do I translate an expression with an addition assignment operator to math notation?

I feel really stupid asking this, but what is the correct way to write the second line of the following example in math notation? Example (JavaScript) var x = 2, y = 2; x += 2 * y; // x = x + 2 * y Would it be written as x := x + 2y?
j.doe
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What is the sigma representation of adding two or more vectors with an identical number of dimensions into one vector?

What is the sigma representation of adding two or more vectors with an identical number of dimensions into one vector? For example, something like this: $$ [x_1,y_1,z_1,\dots,n_1]+[x_2,y_2,z_2,\dots,n_2]+[x_3,y_3,z_3,\dots,n_3]+\dots+…
soundslikefiziks
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Notation Question : $i(n,k)$ denote the number of permutation $\sigma \in S_n$ with $i(\sigma) = k$

Notation Question : Below is the excerpt from a textbook : $i(n,k)$ denote the number of permutation $\sigma \in S_n$ with $i(\sigma) = k$ that is $k$ inversions. from the above statement which set does $S_n$ denote for? [edit: additional…
Beverlie
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How is this letter or symbol pronounced mathematically?

1)How is this letter or symbol pronounced mathematically? $$\overline k$$ 2) $'$ is this sign just a symbol of derivative? For example: $$k'$$ Do we only understand this as a derivative?
Student
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Is it possible to compute $(a+b)\times(c+d)$ with a calculator without memory?

I'm implementing a simple calculator which can only do operations sequentially, one at a time. Expressions of the form: value1 value2 value3 value4 are interpreted as ((value1 value2) …
Frank Kusters
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Infinitary union

I came across $$ x \in \bigcup\limits_{i=1}^\infty A_i $$ and some other notations similar to this one. I wonder if i can use this notation, let's say for intervals, for example $$ x \in \bigcup\limits_{k \in \mathbb Z}…
mxaxc
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