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: 
liealgebras× 740
algebraic structures which were introduced to study the concept of infinitesimal transformations. The term "Lie algebra" (after Sophus Lie) was introduced by Hermann Weyl in the 1930s…

polynomials× 738
Questions in which polynomials (single or several variables) play a key role. It is typically important that this tag is combined with other tags; polynomials appear in very different contexts. Please…

oa.operatoralgebras× 734
Algebras of operators on Hilbert space, C^*algebras, von Neumann algebras, noncommutative geometry

riemanniangeometry× 719
a subfield of Differential Geometry, which specifically studies "Riemannian Manifolds", manifolds with "Riemannian Metrics", which means that they are equipped with continuous i…

ho.historyoverview× 698
History and philosophy of mathematics, biographies of mathematicians, mathematics education, recreational mathematics, communication of mathematics.

algorithms× 674 
primenumbers× 643
Questions where prime numbers play a keyrole, such as: questions on the distribution of prime numbers (twin primes, gaps between primes, Hardy–Littlewood conjectures, etc); questions on prime numbers…

stochasticprocesses× 636
a collection of random variables usually indexed by a totally ordered set.

arithmeticgeometry× 634 
na.numericalanalysis× 615
Numerical algorithms for problems in analysis and algebra, scientific computation

computationalcomplexity× 612
computational complexity theory; complexity classes, such as P, NP, PSPACE, and so on; resourcelimited computation; NPcompleteness and other completeness concepts; oracle analogues of complexity cla…

geometry× 602
Deprecated; please use a more specific tag.

ellipticcurves× 583
an algebraic curve of genus one with some additional properties. Questions with this tag will often have the toplevel tags nt.numbertheory or ag.algebraicgeometry in addition; …

sg.symplecticgeometry× 582
Hamiltonian systems, symplectic flows, classical integrable systems

differentialequations× 579
Ordinary or partial differential equations. Delay differential equations, neutral equations, integrodifferential equations. Wellposedness, asymptotic behavior, and related questions.

fourieranalysis× 530 
algebraicnumbertheory× 530 
differentialtopology× 526
The study of differentiable manifolds and differentiable maps. One fundamental problem is that of classifying manifolds up to diffeomorphism. Differential topology is what Poincaré understood as topol…

analyticnumbertheory× 511
A beautiful blending of real/complex analysis with number theory. The study involves distribution of prime numbers and other problems and helps giving asymptotic estimates to these.

modularforms× 510
Questions about modular forms and related areas

cohomology× 500 
biglist× 487
Questions designed to generate a "big list" of certain results, examples, conjectures, etc. via many individual answers, each contributing one or a few instances. Such a question should typically be i…

banachspaces× 456
a complete normed vector space: A vector space equipped with a norm such that every Cauchy sequence converges.

oc.optimizationcontrol× 441
Operations research, linear programming, control theory, systems theory, optimal control, game theory

modeltheory× 430
the branch of mathematical logic which deals with the connection between a formal language and its interpretations, or models.

tagremoved× 429
to be used only when retagging highly(!) offtopic questions where none of the actual tags would make sense; all actual tags the questioner has used are removed and something is needed to…

qa.quantumalgebra× 422
Quantum groups, skein theories, operadic and diagrammatic algebra, quantum field theory

probabilitydistributions× 409 
algebraiccurves× 401 
knottheory× 393
dealing with embedding of curves in manifolds of dimension 3. A knot is a single circle embedded in the affine space of dimension 3 as a smooth curve not crossing itself. Many knot inva…

highercategorytheory× 372 
modulispaces× 367
Given a concrete category C, with objects denoted Obj(C), and an equivalence relation ~ on Obj(C) given by morphisms in C. The moduli set for Obj(C) is the set of equivalence classes with respect to …

discretegeometry× 366
Finite or discrete collections of geometric objects. Packings, tilings, polyhedra, polytopes, intersection, arrangements, rigidity.

harmonicanalysis× 365 
computabilitytheory× 364
computable sets and functions, Turing degrees, c.e. degrees, models of computability, primitive recursion, oracle computation, models of computability, decision problems, undecidability, Turing jump, …

smoothmanifolds× 363
Smooth manifolds and smooth functions between them. For manifolds with additional structure, see more specific tags, such as [riemanniangeometry]. For more topological aspects, see [differentialtopo…
