# Tags

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.

 Type to find tags:
 cardinals× 1048 for questions about cardinals and related topics such as cardinal arithmetics, regular cardinals and cofinality. Do not confuse with [large-cardinals] which is a technical concept about st… computational-complexity× 1043 Computational complexity, a part of theoretical computer science that deals with understanding how efficiently a problem can be solved. normed-spaces× 1043 A vector space $E$, generally over the field $\mathbb R$ or $\mathbb C$ with a map $\lVert \cdot\rVert\colon E\to \mathbb R_+$ satisfying some conditions. model-theory× 1023 the study of (classes of) mathematical structures (e.g. groups, fields, graphs, universes of set theory) using tools from mathematical logic. Objects of study in model theory are mode… combinations× 1012 subsets of a given size of a given finite set. All questions for this tag have to directly involve combinations; if instead the question is about binomial coefficients, use that tag. expectation× 1009 For questions about the expectation of a random variable: computations, upper/below bounds, etc... abelian-groups× 982 Should be used with the (group-theory) tag. A group $(G,*)$ is said to be abelian if $a*b=b*a$ for all $a,b\in G.$ analytic-number-theory× 971 Questions on the use of the methods of real/complex analysis in the study of number theory. contour-integration× 969 Questions on the evaluation of integrals along a locus in the complex plane. lp-spaces× 959 For questions about $L^p$ spaces, that is, given a measure space $(X,\mathcal F,\mu)$, the vector space of equivalence class of measurable functions with $p$-th power of the absolute value integrable.… mathematical-physics× 956 "Mathematical physics consists of the application of mathematics to problems in physics and the development of mathematical methods suitable for such applications and for the formulation of physical t… conic-sections× 954 Questions on conic sections and their properties; the curves formed by the intersection of a plane and a cone. Circles, ellipses, hyperbolas, and parabolas are examples of conic sections. tensor-products× 951 Tensor products allow us to build "linear" objects from "multilinear" ones. It can refer to: basic ones from linear algebra/module theory, or more sophisticated versions from differential/algebraic ge… functional-equations× 949 used for problems where the goal is to find all functions satisfying the given equation (and maybe some other conditions). So in this case, solving the equation means… solution-verification× 933 For posts looking for feedback or verification of a proposed solution. inner-product-space× 922 a vector space equipped with an inner product. The inner product is a generalisation of the "dot" product often used in vector calculus. homotopy-theory× 919 homotopic, if one of them can by continuously deformed to another. This gives rise to an equivalence relation. A group called homotopy group can be obtained from the equivalence clas… factoring× 919 For questions about finding factors of e.g. integers or polynomials game-theory× 916 The study of competitive and non-competitive games, equilibrium concepts such as Nash equilibrium, and related subjects. Combinatorial games such as Nim are under (combinatorial-game-theory), and algo… conditional-probability× 916 the probability that an event occurs given something else has already occurred. numerical-linear-algebra× 898 Questions on the various algorithms used in linear algebra computations (matrix computations). boolean-algebra× 890 structures which behave similar to a power set with complement, intersection and union. Questions regarding Boolean algebras as structures, or regarding functions defined from/to … factorial× 889 Questions on the factorial function, $n!=n\times(n-1)\times\cdots\times1$. Consider using the tag (gamma-function) if dealing with noninteger arguments. coordinate-systems× 872 Questions on coordinate systems, a geometric method where a point in n-dimensions is assigned a corresponding n-tuple of numbers. extension-field× 856 for questions about extension fields in abstract algebra. An extension field of a field K is just a field containing K as subfield, but interesting questions arise with them. Use this… 3d× 838 is for things related to 3-dimensions. For geometry of 3-dimensional solids, please use instead (solid-geometry). For geometry that is not on a plane, but otherwise agnostic of dimensions… brownian-motion× 836 Questions related to Brownian motion, a continuous stochastic process denoted by $W_t$, $t\geq 0$, with independent increments, such that $W(t)-W(s)$ is normally distributed, with $0$ mean and varianc… closed-form× 835 any representation of a mathematical expression in terms of "known" functions, "known" usually being replaced with "elementary". big-list× 808 Questions asking for a "big list" of examples, illustrations, etc. Ask only when the topic is compelling, and please do not use this as the only tag for a question. computability× 799 Questions about Turing computability and recursion theory, including the halting problem and other unsolvable problems. Questions about the resources required to solving particular problems should be … distribution-theory× 768 for questions about Schwartz distributions, also known as Generalised Functions. For questions about "probability distributions", use (probability-distributions). For questions about dist… predicate-logic× 753 Questions concerning predicate calculus, i.e. the logic of quantifiers. algebraic-curves× 746 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… regression× 744 Questions on (linear or nonlinear) regression, the fitting of functions that best approximate empirical data. surfaces× 738 For questions about surfaces. axiom-of-choice× 738 a common set-theoretic axiom with many equivalents and consequences. This tag is for questions on where we use it in certain proofs, and how things would work without the assump…