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A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

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for questions in graph theory. Here a graph is a collection of vertices and connecting edges. Use (graphing-functions) instead if your question is about graphing or plotting functions.
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Convergence of sequences and different modes of convergence.
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for questions seeking external references (books, articles, etc.) about a particular subject. Please do not use this as the only tag for a question.
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Questions on partial (as opposed to ordinary) differential equations.
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for questions about rings, which are a type of algebraic structure studied in abstract algebra and algebraic number theory.
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the process of choosing the "best" value among possible values. They are often formulated as questions on the minimization/maximization of functions, with or without constraints.
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Questions about algebraic methods and invariants to study and classify topological spaces: homotopy groups, (co)-homology groups, fundamental groups, covering spaces, and beyond.
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Questions about the evaluation of specific definite integrals.
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Questions involving complex numbers, that is numbers of the form $a+bi$ where $i^2=-1$ and $a,b\in\mathbb{R}$.
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For questions about vector spaces and their properties. More general questions about linear algebra belong under the [linear-algebra] tag. A vector space is a space which consists of elements called "…
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Questions about evaluating summations, especially finite summations. For infinite series, please consider the (sequences-and-series) tag instead.
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Questions about commutative rings, their ideals, and their modules.
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one where small changes of input result in correspondingly small changes of output. Use this tag for questions involving this concept. As there are many mathemati…
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sets on which a metric is defined. A metric is a generalization of the concept of "distance" in the Euclidean sense. Metric spaces arise as a special case of the more general notion …
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For questions about the formulation of a proof. This tag should not be the only tag for a question and should not be used to ask for a proof of a statement.
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A stochastic, or random, process describes the correlation or evolution of random events. It is used to model stock market fluctuations and electronic/audio-visual/biological signals. Among the most w…
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Questions on numerical analysis/numerical methods; methods for approximately solving various problems that often do not admit exact solutions.
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numbers associated to a linear operator from a vector space $V$ to itself: $\lambda$ is an eigenvalue of $T\colon V\to V$ if the map $x\mapsto \lambda x-Tx$ is not injective. An eigenv…
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for questions about fields and field theory in abstract algebra. A field is, roughly speaking, an algebraic structure in which addition, subtraction, multiplication, and division of eleme…
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For questions whose answers can't be objectively evaluated as correct or incorrect, but which are still relevant to this site. Please be specific about what you are after.
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structures containing objects and arrows between them. Most mathematical structures can serve as objects of a category, with structure morphisms as arrows. Many constructions are specia…
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natural numbers greater than 1 not divisible by any smaller number other than 1. This tag is intended for questions about, related to, or involving prime numbers.
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refers to questions asked in the field of Group Theory which, in particular, focus on the groups of finite order.
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For questions related to permutations, which can be viewed as re-ordering a collection of objects.
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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…
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Mathematical questions about Algorithms, including the analysis of algorithms, combinatorial algorithms, proofs of correctness, invariants, and semantic analyses. See also (computational-mathematics)…
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for questions and problems involving vectors, e.g., in an Euclidean plane or space. More abstract questions, might better be tagged vector-spaces, linear-algebra, etc.
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a system of integer arithmetic based on the congruence relation $a \equiv b \pmod{n}$ which means that $n$ divides $a-b$.
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Questions about maps from a probability space to a measure space which are measurable.
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Fourier analysis, also known as spectral analysis, encompasses all sorts of Fourier expansions, including Fourier series, Fourier transform and the discrete Fourier transform (and relatives). The non-…
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For questions about mathematical induction, a method of mathematical proof. Mathematical induction generally proceeds by proving a statement for some integer, called the base case, and then proving t…
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Questions related to real and complex logarithms.
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the branch of functional analysis that focuses on bounded linear operators, but it includes closed operators and nonlinear operators. Operator theory is also concerned with the stu…
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For questions about modules over rings, concerning either their properties in general or regarding specific cases.
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In mathematics, a linear map (also called a linear mapping, linear transformation or, in some contexts, linear function) is a mapping V → W between two modules (including vector spaces) that preserves…
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for set theory topics typically studied at the advanced undergraduate or graduate level. These include cofinality, axioms of ZFC, axiom of choice, forcing, set-theoretic independence, larg…