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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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a category with "morphisms between morphisms".
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For questions regarding groups of even prime power order, as distinct from p-groups in general. Topics include 2-groups of maximal class, 2-groups as Sylow subgroups, and the conjecture that almost al…
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For things related to 3 dimensions. For geometry of 3-dimensional solids, please use instead (solid-geometry). For non-planar geometry, but otherwise agnostic of dimensions, perhaps (euclidean-geometr…
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Questions specifically about 4-dimensional manifolds
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For questions about proving and manipulating the AM-GM inequality. To be used necessarily with [tag:inequality] tag.
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For questions about and related to the abc conjecture.
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categories that possess most of properties of categories of modules over a ring, e.g. abelian group structure on morphisms, existence of kernels and cokernels of morphisms, exis…
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Should be used with the (group-theory) tag. A group $(G,*)$ is said to be abelian if $a*b=b*a$ for all $a,b\in G.$
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In mathematics, particularly in algebraic geometry, complex analysis and number theory, an abelian variety is a projective algebraic variety that is also an algebraic group, i.e., has a group law that…
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for questions related to absolute continuity, which is a smoothness property of functions stronger than that of continuity and uniform continuity.
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for questions related to absolute convergence a series.
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For questions about or involving the absolute value function.
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For questions about groups, rings, fields, vector spaces, modules and other algebraic objects. Associate with related tags like group-theory, ring-theory, modules, etc. to clarify which topic of abstr…
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For questions about accessible categories, accessible functors, and their properties. Use in conjonction with the tag (category-theory).
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An example of a total computable function that is not primitive recursive; appears in the literature in many variants. The original three argument variant can be used to define the Ackermann numbers.
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a discipline that uses mathematics and statistics to assess risk. The mathematics involved in actuarial science includes probability, statistics, finance, life insurance mathemat…
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For questions dealing with additive or pre-additive categories.
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about giving combinatorial estimates of addition and subtraction operations on Abelian groups or other algebraic objects. Key words: sum set estimates, inverse theorems, grap…
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For questions on groups and rings of adeles, self-dual topological rings built on an algebraic number field.
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a square matrix used to represent a finite graph. The elements of the matrix indicate whether pairs of vertices are adjacent or not. In the special case of a finite simple graph…
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For questions about adjoint functors from category theory. Use in conjunction with the tag (category-theory).
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For questions about adjoint operators in inner product spaces. For adjoint functors from category theory, use the tag (adjoint-functors).
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Questions asking for advice on various mathematical matters. Be careful that your question is answerable, and also that it is not a polling question (e.g. "What is the best / your favorite way to..."…
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for questions about algebraic geometry that focus on affine space. For affine mappings in linear algebra (i.e. linear mappings plus translations), please use the linear-algebra tag or another appropri…
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The spectrum of a commutative ring with unit is the set of prime ideals endowed with the Zariski topology. One can define a sheaf of rings on this space : to each Zariski-open set is assigned a commut…
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for questions related to an affine variety over an algebraically-closed field.
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For questions about Airy functions, the solution to Schrödinger's equation for a particle confined within a triangular potential well and for a particle in a one-dimensional constant force field.
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For questions about the Alexandroff double circle, also called "Concentric Circles" in Steen & Seebach's "Counterexamples in Topology".
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For problems involving algebraic methods in combinatorics (especially group theory and representation theory) as well as combinatorial methods in abstract algebra.
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an algebraic variety of dimension one. An affine algebraic curve can be described as the zero-locus of $n-1$ independent polynomials of $n$ variables in affine $n$-space over a f…
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for questions related to solving equations involving polynomials.